JP6226457B2 - Oxygen-added ScN crystal thin film, method for producing the same, electrode and electronic device - Google Patents

Description

  The present invention relates to an oxygen-added ScN crystal thin film, a manufacturing method thereof, an electrode, and an electronic device.

  In order to improve the performance of displays, high-performance semiconductor materials are required. IGZO, which has become a hot topic in recent years, has attracted attention as an effective material for saving labor of displays and the like because it exhibits a large electron mobility with respect to amorphous silicon.

  In the advancement of solar cells, it is essential to improve the performance of electrode materials. Not only the performance of the light absorption layer that absorbs light and generates electrons and holes, but also the efficiency of electrons and holes generated there. An electrode for frequently taking out (collecting current) is necessary, and high performance of the collecting electrode is required.

  Even in the case of increasing the efficiency of LEDs, it is important not only to improve the quality of the active layer that emits light, but also to reduce the resistance of the electrode material for injecting current there.

  In these applications, it is necessary to control the interface with dissimilar materials, and it is necessary to develop materials that take into account chemical reactivity and surface stability.

  Since the electrical conductivity of a general semiconductor is defined by “main carrier concentration × main carrier mobility”, it is necessary to increase both of them simultaneously.

  However, doping, which is a general technique for increasing the concentration of main carriers, is equivalent to the introduction of crystal defects, and there is a trade-off that the mobility of main carriers decreases due to doping. For example, in the past semiconductors such as zinc oxide and gallium nitride, the above trade-off is remarkable, and the effect of increasing the concentration of main carriers due to doping is reduced by the decrease in mobility.

  As a general problem, i) develop a semiconductor having high mobility that can be used as an electrode material or a material of an electronic component, and ii) further, a laminated structure of nitride or oxide. Develop semiconductors with chemical stability to form, iii) have as wide a band gap as possible in considering applications to electrodes used in solar power generation and LEDs, thereby translucent Development of a semiconductor having a property.

  On the other hand, with the progress of optical / electronic device research of group IIIb nitrides represented by GaN, application to the semiconductor field such as ScN is expected.

For example, in Non-Patent Document 1, a ScN film was synthesized by the HVPE method, and a mobility of up to 158 (cm ² / Vs) at room temperature and an electron concentration of 10 ²⁰ -10 ²¹ (cm ^-3 ) were obtained. Has been reported. However, as shown in FIG. 3 of the same document, the mobility is highly variable, and reproducibility was not obtained. Moreover, although the conductivity control is tried, the cause of the conductivity has not been found. In particular, a raw material containing halogen is used, and various factors such as non-stoichiometry of ScN and mixing of halogen are duplicated, which makes it difficult to control the conductivity. Furthermore, the translucency was low due to defects, and the optical material was inferior.

Non-Patent Document 2 reports that the ScN film was formed on the sapphire r surface by reactive sputtering using Sc metal as a raw material. The ScN film formed in this document has an electron concentration of the order of 10 ²¹ (cm ⁻³ ), and corresponds to the high electron concentration of the examples disclosed in Non-Patent Document 1. The electron mobility is a value larger than that of Non-Patent Document 1 when compared only in the examples disclosed in Non-Patent Document 1 where the electron concentration is as high as that of Non-Patent Document 2. However, when viewed as a whole, it remains below 100 (cm ² / Vs). In addition, it is foreseen that the electron concentration should decrease because the contamination from the vacuum chamber is reduced by forming a film using an ultra-high vacuum vacuum chamber, but the cause of the conductivity is not specified. The physical property control was incomplete.

Furthermore, as reported in Non-Patent Documents 3 to 7, the present inventors also epitaxially grown a ScN thin film on an MgO substrate or a sapphire substrate using the MBE method, and 50-130 (cm ² / Vs) at room temperature. ) Mobility of 10 ¹⁹ -10 ²² (cm ^-3 ), and the crystallinity was excellent. However, the factors governing conductivity were not known, and physical property control was incomplete.

J. P. Dismukes et al., Journal of Crystal Growth, 13/14, 1972, 365-370 J. N. Gregoire et al., Journal of Applied Physics, 104, 2008, 074913-1-074913-7 Ogaki et al., “Preparation of (110) Oriented ScN Thin Films and Their Electrical Properties” The Ceramic Society of Japan 2012 Annual Meeting 2012/03/19-2012/03/21 Kyoto University Yoshida Campus, Kyoto City Ogaki et al., “Preparation of Scandium Nitride Thin Films by MBE” The Ceramic Society of Japan 2010 Annual Meeting, 2010/03/22-2010/03/24 Tokyo University of Agriculture and Technology, Koganei Campus, Koganei Ogaki et al., “Electrical Properties of ScN Thin Films Prepared by MBE” The Japan Ceramic Society 2011 Annual Meeting 2011/03/16-2011/03/18 Shizuoka University Hamamatsu Campus, Hamamatsu Ogaki et al., “Fabrication of scandium nitride thin film on sapphire substrate” The 24th Autumn Symposium of the Ceramic Society of Japan 2011/09/07-2011/09/09 Hokkaido University (Higher Education Promotion Organization), Sapporo Ogaki et al., "Fabrication of scandium nitride thin film on sapphire r-plane substrate by MBE method" The 25th Autumn Symposium of the Ceramic Society of Japan 2012/09/19-2012/09/21 Nagoya University, Higashiyama Campus, Nagoya City

In the present invention, electrical characteristics with an electron mobility of 90 (cm ² / V · sec) or more and an electron concentration of 1 × 10 ²⁰ (cm ⁻³ ) or more can be obtained with high reproducibility, high translucency, and surface stability. It is an object to obtain an excellent ScN crystal thin film, a manufacturing method thereof, an electrode, and an electronic device.

  In order to solve the above-mentioned problems, the present inventors have examined the existence of the possibility of electron doping, the occurrence of start-up hybridization due to electron doping, etc. by electronic state simulation. As a result, ScN can be doped with oxygen. In addition, material design was performed with the knowledge that no migration hybridization occurred due to doping. Then, oxygen was actually added to ScN, and as a result, it was found that electrical characteristics (hole mobility, carrier concentration) higher than those of the ScN thin film were obtained with good reproducibility, and the present invention was completed.

  The present invention has the following configuration.

[1] A ScN crystal thin film to which oxygen is added, wherein the oxygen addition amount is 1 × 10 ²⁰ (cm ⁻³ ) or more and 1 × 10 ²¹ (cm ⁻³ ) or less. ScN crystal thin film.

  [2] The oxygen-added ScN crystal thin film according to the first aspect, wherein the oxygen addition amount is uniform from one side to the other side.

  [3] In the first or second aspect of the invention, a crystallinity having a high crystallinity with a full width at half maximum (FWHM) of a rocking curve of a crystal plane perpendicular to a growth plane obtained by X-ray diffraction measurement being 0.5 ° or less. An oxygen-added ScN crystal thin film.

  [4] The oxygen-doped ScN crystal thin film according to any one of the first to third inventions, wherein the composition ratio Sc / (N + O) is 1.

  [5] When a ScN crystal is grown on one surface of an oxide substrate by using molecular beam epitaxy as a raw material with Sc having a purity of 99.9% or more and atomic nitrogen, the oxide substrate is heated to a temperature of 700 ° C. to 1100 ° C. A method for forming an oxygen-added ScN crystal thin film, characterized by heating to a range.

[6] The method for forming an oxygen-added ScN crystal thin film according to the fifth invention, wherein the oxide substrate is an MgO substrate or an α-Al ₂ O ₃ substrate.

[7] In the fifth or sixth invention, the one surface is made of MgO (100) surface, MgO (110) surface, α-Al ₂ O ₃ (m surface) and α-Al ₂ O ₃ (r surface). A method for forming an oxygen-added ScN crystal thin film, which is any one of the above.

  [8] The oxygen according to any one of the fifth to seventh aspects, wherein the growth rate when forming the ScN crystal thin film is 50 (nm / h) or more and 200 (nm / h) or less. Method for forming added ScN crystal thin film.

  [9] An electrode comprising any one of the first to fourth oxygen-added ScN crystal thin films.

  [10] An electronic device having a semiconductor material portion and two or more electrodes connected to the semiconductor material portion, wherein at least one of the electrodes is the electrode of the ninth invention .

According to the present invention, since the above-described configuration is adopted, an electric property having an electron mobility of 90 (cm ² / V · sec) or more and an electron concentration of 1 × 10 ²⁰ (cm ⁻³ ) or more can be obtained with good reproducibility. An oxygen-doped ScN crystal thin film having high translucency and excellent surface stability was obtained.

  This oxygen-added ScN crystal thin film can be used as an electrode, whereby an electronic device having excellent electrical characteristics can be produced.

It is a schematic diagram which shows an example of the oxygen addition ScN crystal thin film which is embodiment of this invention, (a) is a top view, (b) is a side view. It is a figure which shows the relationship between the photon energy of N rich and Sc rich oxygen addition ScN, and the transmittance | permeability. It is a figure which shows the mode of visual observation of oxygen addition ScN of N rich and Sc rich. The relationship between the binding energy and the spectral intensity of N-rich oxygen-doped ScN in which no defect level exists in the band gap. The binding energy and the spectral intensity of Sc-rich oxygen ScN in which the defect level is formed at a high concentration in the band gap. It is a figure shown in contrast with the relationship. It is a figure which shows typically the MBE apparatus used with the manufacturing method of this invention. It is a figure which contrasts and shows the wavelength dependence of the emission spectrum of favorable plasma and incomplete plasma. It is a figure which shows typically the structural example which applied the oxygen addition ScN of this invention to the LED element. It is a figure which shows typically the structural example which applied the oxygen addition ScN of this invention to the solar cell. FIG. 4 is a graph showing oxygen / scandium ratios of Example 1, Comparative Example 4, and Comparative Example 6.

  Hereinafter, an oxygen-added ScN crystal thin film, a manufacturing method thereof, an electrode, and an electronic device, which are embodiments of the present invention, will be described with reference to the accompanying drawings.

  First, an oxygen-added ScN crystal thin film that is an embodiment of the present invention will be described.

FIG. 1 is a schematic view showing an example of an oxygen-added ScN crystal thin film according to an embodiment of the present invention. In the figure, the oxide substrate 10, 11 is oxygenated ScN crystal thin film, 11a is the surface of the oxygenated ScN crystal thin film, 11b the back surface of oxygenates ScN film, 10a is the upper surface of the oxide _{substrate, t 11} oxygenator This is the thickness of the ScN thin film 11.

As the oxide substrate 10, an MgO substrate, α-Al ₂ O ₃ or the like can be used. The oxygen-added ScN crystal thin film 11 is epitaxially grown on the oxide substrate 10 by molecular beam epitaxy (hereinafter also referred to as MBE), and the amount of oxygen added is 1 × 10 ²⁰ (cm ⁻³ ) or more and 1 ×. It is 10 ²¹ (cm ⁻³ ) or less. If the amount of oxygen added is less than this range, the electron concentration will be too low to obtain high conductivity, and in particular, if the total anion concentration combined with the oxygen and nitrogen concentrations is too low, it will be translucent. One of the causes of deterioration. On the other hand, if the amount of oxygen added is greater than this range, the mobility will be significantly reduced due to excess oxygen, and the conductivity will be impaired. By adding oxygen, it is possible to achieve both high electron concentration and high mobility. In addition, conductivity control using oxygen concentration as a scale becomes possible. In the oxygen-added ScN crystal thin film 11, the oxygen addition amount is preferably uniform from the one surface side 11a to the other surface side 11b. “Oxygen addition amount is uniform” means that the variation in the addition amount is within ± 20%. When the Sc / (O + N) ratio is close to 1 and the oxygen addition amount is uniform in this way, high conductivity can be realized over the entire thin film, and the translucency deteriorated due to the formation of defect levels. Can be suppressed. In particular, in the vicinity of the surface 11a, it is easy to ensure the uniformity of the Sc / (O + N) ratio by avoiding non-uniformity in which the oxygen concentration decreases, thereby ensuring stability and reducing material deterioration in the atmosphere. Can be suppressed. That is, the surface stability is excellent without inducing oxidation of the surface due to defects near the surface of the element having the ScN thin film as a constituent element. Further, the oxygen-added ScN crystal thin film 11 preferably has a high degree of crystallinity in which the full width at half maximum (FWHM) of the rocking curve of the crystal plane perpendicular to the growth plane obtained by X-ray diffraction measurement is 0.5 ° or less. When the half width is 0.5 ° or less, the crystallinity is high. The oxygen-added ScN crystal thin film 11 preferably has a composition ratio Sc / (N + O) of 0.999 or more and 1.001 or less, particularly preferably 1. When the composition ratio Sc / (N + O) exceeds 1, light absorption is caused by interstitial scandium and the translucency deteriorates. When the composition ratio Sc / (N + O) is less than 1, disturbance is introduced into the electron orbit of scandium forming a conduction band, and the mobility Cause a decline. Therefore, when the composition ratio is 1, an advantage of being excellent in both conductivity and translucency can be obtained. ScN, which is a good translucent electrode, exhibits high light transmittance in a region with a photon energy of 2 eV or less, whereas ScN into which defects such as interstitial scandium are introduced has a reduced transmittance. FIG. 2 shows an example of the relationship between the photon energy and the transmittance of N-rich and Sc-rich oxygen-added ScN. Further, FIG. 3 shows a visual appearance of N-rich and Sc-rich oxygen-added ScN. ScN having a preferable translucency shows a transparent yellow-orange color visually, whereas the translucency deteriorates. The ScN has a color close to gray.

  Furthermore, as an electronic structure for ensuring translucency, it is necessary that no defect level exists in the band gap, and when the defect level is formed at a high concentration in the band gap, the gray level is visually observed. This corresponds to a state that exhibits a color close to. FIG. 4 shows the relationship between the binding energy of N-rich oxygen-added ScN in which no defect level is present in the band gap and the spectral intensity. The binding energy of Sc-rich oxygen ScN in which the defect level is formed at a high concentration in the band gap. And contrast with the spectral intensity.

  Next, the manufacturing method of the oxygen addition ScN crystal thin film of this invention is demonstrated. FIG. 5 is a diagram schematically showing an MBE apparatus used in the manufacturing method of the present invention.

  In the figure, RP is a rotary pump, TMP is a turbo molecular pump, SIP is a sputter ion pump, and RHEED is a backscattered electron diffraction apparatus.

First, an oxide substrate is disposed at a predetermined position in the vacuum chamber of the MBE apparatus. Next, the inside of the vacuum chamber is evacuated, and the pressure is reduced to a range of 10 ⁻¹⁰ Torr to 10 ⁻⁸ Torr. Then, in a state where the oxide substrate is heated to a growth temperature in a range of 700 ° C. to 1100 ° C., the oxide substrate is rotated in a direction parallel to one surface of the oxide substrate, and Sc and N as raw materials are supplied to the one surface. A ScN crystal thin film is formed. When the film thickness reaches a predetermined value, the supply of raw materials is stopped and the film formation is stopped. In the present invention, by heating the oxide substrate at the above temperature, oxygen is added from the oxide substrate to the ScN crystal thin film, and an oxygen-added ScN crystal thin film is obtained.

  In the present invention, nitrogen is supplied through a discharge plasma cell. By using a discharge plasma cell in which the shape and cleanliness of the discharge tube in the cell are optimized, atomic nitrogen with an extremely good radical state can be supplied. The crystallinity of the ScN crystal thin film can be improved. The state of the discharge plasma cell can be known from its emission spectrum. Atomic nitrogen gives three emission lines in a wavelength region of 750 to 900 nm, and one molecular nitrogen gives many emission lines in a wavelength region of 250 to 450 nm. The state in which atomic nitrogen is supplied is a state in which three emission lines in the region of 750 to 900 nm are strongly observed in the emission spectrum of plasma. In particular, in this application, compared with Non-Patent Documents 4 to 7. In particular, the plasma state in which these three bright lines appeared strongly was maintained. FIG. 6 shows the wavelength dependence of the emission spectrum of a good plasma in which atomic nitrogen is actively generated and an incomplete plasma in which molecular nitrogen is dominant. Whether the crystallinity of ScN is high or low can be determined by the full width at half maximum (FWHM). The narrower the full width at half maximum, the higher the crystallinity.

In the present invention, as described above, an MgO substrate, an α-Al ₂ O ₃ substrate or the like can be used as the oxide substrate, and in particular, an MgO (100) surface, an MgO (110) surface, an α-Al ₂ substrate. Since an epitaxially grown film with a uniform crystal lattice is obtained by forming a film on O ₃ (m-plane) and α-Al ₂ O ₃ (r-plane), these substrates must be formed to achieve high mobility. It is preferable to use it.

In the present invention, film formation is performed so that the amount of oxygen added is 1 × 10 ²⁰ (cm ⁻³ ) or more and 1 × 10 ²¹ (cm ⁻³ ) or less. The amount of oxygen added can be controlled by the growth temperature and the amounts of atomic nitrogen and scandium supplied during the growth.

  The growth rate when forming the ScN crystal thin film is set to 50 (nm / h) or more and 200 (nm / h) or less. When the growth rate is in the above range, there is an advantage that the oxygen supply amount can be easily controlled in synthesizing the oxygen-added ScN by means of oxygen supply from the substrate.

  In addition, by heating the oxide substrate to a growth temperature in the range of 700 ° C. to 1100 ° C., the oxygen supply amount can be easily controlled when synthesizing the oxygen-added ScN by means of supplying oxygen from the substrate. There is.

  According to the production method of the present invention, both high electron concentration and high mobility can be realized by adding oxygen. In addition, conductivity control using oxygen concentration as a scale becomes possible.

  In addition, by making the oxygen addition amount uniform from the one surface 11a side to the other surface 11b side in the oxygen-added ScN crystal thin film 11 to be formed by the manufacturing method of the present invention, it has a sharp absorption unit at a short wavelength. Thus, a highly translucent semiconductor is realized. Further, the formation of defect levels in the vicinity of the surface is prevented, surface stability is ensured, and material deterioration in the atmosphere can be suppressed.

  In manufacturing using a substrate other than an oxide, the substrate oxygen is used as an oxygen source by forming a film while introducing a small amount of oxygen gas into the film-forming vacuum chamber in addition to scandium and atomic nitrogen. It is also possible to form a film without any problems.

  Next, an electrode using the oxygen-added ScN crystal thin film of the present invention will be described.

  There are three methods for applying oxygen-added ScN as an electrode. The first mode is a means for forming an oxygen-added ScN thin film on an oxide substrate, laminating a semiconductor layer made of a semiconductor such as gallium nitride on the surface, and using the oxygen-added ScN as a lower electrode. is there. The second embodiment is a method of forming an oxygen-added ScN film on a semiconductor or a semiconductor laminated structure having an oxide semiconductor such as zinc oxide or copper oxide as a surface, and applying this oxygen-added ScN as an upper electrode. . In these embodiments, since the manufacturing method is to form ScN on the oxide, oxygen-added ScN can be formed by supplying oxygen from the oxide layer in contact with ScN. In the third embodiment, oxygen-added ScN is formed as an electrode on the upper part of a semiconductor layer containing no oxygen as a main component, such as gallium nitride. In this embodiment, oxygen in the lower component layer is used as an oxygen source. Therefore, in addition to atomic nitrogen and scandium, an oxygen-added ScN electrode layer is formed while supplying oxygen gas as an oxygen source.

  Next, an electronic device using the electrode will be described.

  By using the oxygen-added ScN as an electrode, the following electronic device can be configured.

  The first example is a light-emitting diode element using oxygen-added ScN as a lower electrode. Oxygenated ScN, which is characterized by high electron concentration and high electron mobility, has higher conductivity than gallium nitride or the like doped with silicon at a high concentration. Therefore, oxygen-doped ScN, which is an n-type semiconductor, is used as the lower electrode. Then, an LED element with reduced energy loss due to the electrical resistance of the electrode part is constructed by stacking the constituent layers in this order on the n-type semiconductor, active layer, p-type semiconductor, and upper electrode. 7A and 7B schematically show structural examples in which the oxygen-added ScN of the present invention is applied to an LED element. In the figure, 7-a is a p-type layer, 7-b is an active layer, 7-c is an n-type layer, 7-d is an n-side electrode (oxygenated ScN of the present invention), and 7-e is a p-side electrode. is there. In either configuration, the lead wire is bonded to 7-d and 7-e. In particular, this configuration contributes to the improvement of the external quantum efficiency of the LED because it has a characteristic as a transparent electrode for an LED emitting infrared to green light.

  The second example is a solar cell. This is a solar cell element in which the lower electrode of a solar cell configured by stacking a lower electrode, an n-type layer, a p-type layer, and an upper electrode on a substrate has oxygen-doped ScN. FIGS. 8A and 8B schematically show structural examples in which the oxygen-added ScN of the present invention is applied to a solar cell. In the figure, 8-a is a p-type layer, 8-b is an n-type layer, 8-c is an n-side electrode (oxygenated ScN of the present invention), 8-d is a substrate, 8-e is a p-side electrode, 8-f is an antireflection coating, and 8-g is a wide gap p-type layer. Light enters from the 8-f side. FIG. 8B shows a tandem structure that can generate power at two interfaces of (8-b) / (8-c) and (8-c) / (8-g). By making the lower electrode (8-c) oxygen-added ScN, energy loss due to its electric resistance is reduced.

  The oxygen-added ScN crystal thin film, its manufacturing method, electrode and electronic device, which are embodiments of the present invention, are not limited to the above-described embodiments, and various modifications are made within the scope of the technical idea of the present invention. can do. Specific examples of this embodiment are shown in the following examples. However, the present invention is not limited to these examples.

Example 1
An unnitrided sapphire r substrate was placed at a predetermined position in the vacuum chamber of the MBE apparatus having the structure shown in FIG. 5, and the vacuum chamber was evacuated and decompressed to 10 ⁻⁹ Torr. Next, with the substrate heated to 914 ° C., as shown in the figure, the substrate is rotated in a direction parallel to one surface of the substrate, and Sc and N as raw materials are supplied from the respective evaporation cells to one surface of the substrate. Then, an ScN crystal thin film was formed at a film formation rate of about 100 (nm / h). The supply ratio of Sc / N was 1. In the apparatus which acquired the data of the example and the comparative example, when the temperature setting of the scandium evaporation source is set to 1295 ° C. based on the specification of the plasma cell, the exhaust speed and internal structure of the vacuum chamber, the specification of the Sc evaporation source, etc. However, the device configuration is Sc / N supply ratio = 1. FIG. 9 shows the oxygen / scandium ratio of Example 1 as distribution 1. Distributions 2 and 3 are oxygen / scandium ratios of Comparative Examples 4 and 6 described later. Nitrogen was supplied as atomic nitrogen through the discharge plasma. When the film thickness reached about 500 nm, the raw material supply was stopped and the film formation was stopped. During the film formation, oxygen was added from the substrate to the ScN crystal thin film, and the oxygen-added ScN crystal thin film according to the present invention was obtained.

The electron concentration obtained by evaluating the produced oxygen-added ScN crystal thin film by Hall effect measurement is 1.3 × 10 ²⁰ (cm ⁻³ ), which matches the oxygen addition amount, and the mobility is 110 (cm ² / Vs). Further, the actually measured value of the oxygen concentration distribution in the thin film obtained by the secondary ion mass spectrometer is 10 ²⁰ (cm ⁻³ ), and the oxygen concentration in the film is a curve of distribution 1 in FIG. As shown in Fig. 1, it was confirmed that the thin film was uniformly distributed from the surface to the inside. The horizontal axis in FIG. 9 is the sputtering time of the secondary ion mass spectrometer, the increase in time corresponds to the depth from the surface of the analysis site, and the vertical axis is the coefficient of scandium-related ion species and oxygen-related ion species. The ratio, that is, the relative oxygen concentration is shown. The resistivity measured by the van der Poe method at room temperature was 4.3 × 10 ⁻⁴ (Ω · cm). The color of the oxygen-added ScN crystal thin film was yellow-orange with high transparency. Moreover, the half width of the X-ray diffraction was 0.2 °.
(Example 2)
In Example 1, the Sc / N supply ratio was N-rich (a state in which the supply amount was reduced by controlling the evaporation temperature of the Sc supply cell by 4.2 ° C. lower than in Example 1), and An oxygen-added ScN crystal thin film according to the present invention was obtained in the same manner except that the substrate was heated to 910 ° C.

The produced oxygen-added ScN crystal thin film had an electron concentration of 2.6 × 10 ²⁰ (cm ⁻³ ) and a mobility of 113 (cm ² / Vs). Further, the oxygen concentration in the thin film was 10 ²⁰ (cm ⁻³ ), and it was confirmed that oxygen was uniformly distributed in the thin film. The resistivity was 1.6 × 10 ⁻⁴ (Ω · cm). The color of the oxygen-added ScN crystal thin film was yellow-orange with high transparency, and showed the same transmittance characteristics as the spectrum shown as N-rich in FIG. The full width at half maximum was 0.4-0.5 °.
(Example 3)
In Example 1, the supply ratio of Sc / N was N-rich (in a state where the supply amount was reduced by controlling the evaporation temperature of the Sc supply cell by lowering by 4.1 ° C. compared to Example 1), and An oxygen-added ScN crystal thin film according to the present invention was obtained in the same manner except that the substrate was heated to 911 ° C.

The electron concentration of the produced oxygen-added ScN crystal thin film was 5.6 × 10 ²⁰ (cm ⁻³ ), and the mobility was 143 (cm ² / Vs). Further, the oxygen concentration in the thin film was 10 ²⁰ (cm ⁻³ ), and it was confirmed that oxygen was uniformly distributed in the thin film. The resistivity was 7.8 × 10 ⁻⁴ (Ω · cm). The color of the oxygen-added ScN crystal thin film was yellow-orange with high transparency, and showed the same transmittance characteristics as the spectrum shown as N-rich in FIG. The full width at half maximum was 0.4-0.5 °.
Example 4
An oxygen-added ScN crystal thin film according to the present invention was obtained in the same manner except that the substrate was heated to 904 ° C. in Example 1.

The produced oxygen-added ScN crystal thin film had an electron concentration of 3.4 × 10 ²⁰ (cm ⁻³ ) and a mobility of 177 (cm ² / Vs). Further, the oxygen concentration in the thin film was 10 ²⁰ (cm ⁻³ ), and it was confirmed that oxygen was uniformly distributed in the thin film. The resistivity was 1.0 × 10 ⁻⁴ (Ω · cm). The color of the oxygen-added ScN crystal thin film was yellow-orange with high transparency, and showed the same transmittance characteristics as the spectrum shown as N-rich in FIG. The full width at half maximum was 0.3-0.4 °.
(Example 5)
In Example 1, the supply ratio of Sc / N was N rich (in a state where the supply amount was reduced by controlling the evaporation temperature of the Sc supply cell by 4.9 ° C. lower than in Example 1), and An oxygen-added ScN crystal thin film according to the present invention was obtained in the same manner except that the substrate was heated to 902 ° C.

The produced oxygen-added ScN crystal thin film had an electron concentration of 2.3 × 10 ²⁰ (cm ⁻³ ) and a mobility of 135 (cm ² / Vs). Further, the oxygen concentration in the thin film was 10 ²⁰ (cm ⁻³ ), and it was confirmed that oxygen was uniformly distributed in the thin film. The resistivity was 2.2 × 10 ⁻⁴ (Ω · cm). The color of the oxygen-added ScN crystal thin film was yellow-orange with high transparency, and showed the same transmittance characteristics as the spectrum shown as N-rich in FIG. The full width at half maximum was 0.4-0.5 °.
(Example 6)
In Example 1, the supply ratio of Sc / N was N-rich (a state in which the supply amount was reduced by controlling the evaporation temperature of the Sc supply cell to be 4.8 ° C. lower than in Example 1), and An oxygen-added ScN crystal thin film according to the present invention was obtained in the same manner except that the substrate was heated to 903 ° C.

The produced oxygen-added ScN crystal thin film had an electron concentration of 3.7 × 10 ²⁰ (cm ⁻³ ) and a mobility of 146 (cm ² / Vs). Further, the oxygen concentration in the thin film was 10 ²⁰ (cm ⁻³ ), and it was confirmed that oxygen was uniformly distributed in the thin film. The resistivity was 1.2 × 10 ⁻⁴ (Ω · cm). The color of the oxygen-added ScN crystal thin film was yellow-orange with high transparency, and showed the same transmittance characteristics as the spectrum shown as N-rich in FIG. The full width at half maximum was 0.3-0.4 °.
(Example 7)
In Example 1, the sapphire m substrate was used, and the supply ratio of Sc / N was N rich (compared to Example 1, the evaporation temperature of the Sc supply cell was lowered by 4.2 ° C., and the supply amount was controlled. The oxygen-added ScN crystal thin film according to the present invention was obtained in the same manner except that the substrate was heated to 905 ° C.

The produced oxygen-added ScN crystal thin film had an electron concentration of 1.2 × 10 ²⁰ (cm ⁻³ ) and a mobility of 95 (cm ² / Vs). Further, the oxygen concentration in the thin film was 10 ²⁰ (cm ⁻³ ), and it was confirmed that oxygen was uniformly distributed in the thin film. The resistivity was 5.4 × 10 ⁻⁴ (Ω · cm). The color of the oxygen-added ScN crystal thin film was yellow-orange with high transparency, and showed the same transmittance characteristics as the spectrum shown as N-rich in FIG. The full width at half maximum was 0.4-0.5 °.
(Example 8)
In Example 1, the sapphire m substrate was used, and the Sc / N supply ratio was N rich (compared to Example 1, the evaporation temperature of the Sc supply cell was controlled to be lowered by 4.5 ° C. to reduce the supply amount. The oxygen-added ScN crystal thin film according to the present invention was obtained in the same manner except that the substrate was heated to 907 ° C.

The produced oxygen-added ScN crystal thin film had an electron concentration of 1.5 × 10 ²⁰ (cm ⁻³ ) and a mobility of 132 (cm ² / Vs). Further, the oxygen concentration in the thin film was 10 ²⁰ (cm ⁻³ ), and it was confirmed that oxygen was uniformly distributed in the thin film. The resistivity was 3.1 × 10 ⁻⁴ (Ω · cm). The color of the oxygen-added ScN crystal thin film was yellow-orange with high transparency, and showed the same transmittance characteristics as the spectrum shown as N-rich in FIG. The full width at half maximum was 0.3-0.4 °.
Example 9
An oxygen-doped ScN crystal thin film according to the present invention was obtained in the same manner as in Example 1 except that a sapphire m substrate was used and the substrate was heated to 908 ° C.

The electron concentration of the produced oxygen-added ScN crystal thin film was 3.1 × 10 ²⁰ (cm ⁻³ ), and the mobility was 97 (cm ² / Vs). Further, the oxygen concentration in the thin film was 10 ²⁰ (cm ⁻³ ), and it was confirmed that oxygen was uniformly distributed in the thin film. The resistivity was 2.1 × 10 ⁻⁴ (Ω · cm). The color of the oxygen-added ScN crystal thin film was yellow-orange with high transparency, and showed the same transmittance characteristics as the spectrum shown as N-rich in FIG. The full width at half maximum was 0.3-0.4.
(Comparative Example 1)
In Example 1, in addition to the N-rich (state in which the supply amount was reduced by controlling the evaporation temperature of the Sc supply cell to be reduced by 4.9 ° C.), the substrate was heated to 701 ° C., radicals The oxygen-doped ScN crystal thin film of the comparative example was obtained in the same manner as in Example 1 except that the state of the source was changed and the atomic nitrogen ratio was intentionally lowered to make the molecular nitrogen supply amount high. It was.

The produced oxygen-added ScN crystal thin film had an electron concentration of 2.5 × 10 ¹⁹ (cm ⁻³ ) and a mobility of 69 (cm ² / Vs). The resistivity was 3.7 × 10 ⁻³ (Ω · cm). The color of the oxygen-added ScN crystal thin film was yellow-orange with high transparency. The full width at half maximum exceeded 0.5 °.
(Comparative Example 2)
In Example 1, the substrate was made of sapphire m-plane, N-rich (state in which the supply amount was reduced by controlling the evaporation temperature of the Sc supply cell to be lowered by 4.7 ° C.), and the substrate was heated to 803 ° C. In addition to changing the state of the radical source, the ratio of atomic nitrogen was intentionally lowered, and the oxygen supply of the comparative example was similarly performed except that the molecular nitrogen supply amount was high. A ScN crystal thin film was obtained.

The produced oxygen-added ScN crystal thin film had an electron concentration of 4.5 × 10 ¹⁹ (cm ⁻³ ) and a mobility of 44 (cm ² / Vs). The resistivity was 3.1 × 10 ⁻³ (Ω · cm). The color of the oxygen-added ScN crystal thin film was yellow-orange with high transparency. The full width at half maximum exceeded 0.5 °.
(Comparative Example 3)
In Example 1, a sapphire m substrate was used, N-rich (a state in which the supply amount was reduced by controlling the evaporation temperature of the Sc supply cell by 4.6 ° C.), and the substrate was heated to 702 ° C. In addition to changing the state of the radical source in addition to the state, the oxygen-doped ScN crystal of the example was similarly changed except that the atomic nitrogen ratio was intentionally lowered to increase the molecular nitrogen supply amount. A thin film was obtained.

The produced oxygen-added ScN crystal thin film had an electron concentration of 4.2 × 10 ¹⁹ (cm ⁻³ ) and a mobility of 15 (cm ² / Vs). The resistivity was 9.3 × 10 ⁻³ (Ω · cm). The color of the oxygen-added ScN crystal thin film was yellow-orange with high transparency. The full width at half maximum exceeded 0.5 °.
(Comparative Example 4)
In Example 1, the Sc / N supply ratio was set to Sc rich (in comparison with Example 1, the evaporation temperature of the Sc supply cell was increased by 5 ° C. and the supply amount was increased), and the substrate was A comparative oxygen-doped ScN crystal thin film was obtained in the same manner except that the state was heated to 912 ° C.

The produced oxygen-added ScN crystal thin film had an electron concentration of 1 × 10 ²¹ (cm ⁻³ ) and a mobility of 147 (cm ² / Vs). The resistivity was 4.2 × 10 ⁻⁵ (Ω · cm), which exhibited the low resistance characteristic shown in the above example, and the half width was 0.1-0.2 °. However, the color is a color close to gray with low transparency as shown in FIG. 3B, and is as shown by the Sc rich curve in the transmittance characteristics of FIG. The oxygen concentration in this thin film is an average value of 10 ²¹ (cm ⁻³ ), but the measurement result of ion mass spectrometry is very high on the substrate side as shown in distribution 2 in FIG. , Decreased toward the surface, distributed very unevenly, and in the vicinity of the surface, the concentration was as low as 10 ¹⁹ (cm ⁻³ ). Further, in the photoelectron spectroscopy measurement result of FIG. 4, in Example 2, the N-rich pattern in the figure was shown, whereas in the oxygen-added ScN thin film obtained in this comparative example, the binding energy 0.8-1 A state was observed in the vicinity of 0.0 eV, and it was confirmed that a high-concentration defect level was present in the band gap.
(Comparative Example 5)
In Example 1, the supply ratio of Sc / N was set to Sc rich (in a state where the supply amount was increased by controlling the evaporation temperature of the Sc supply cell by increasing it by 4.9 ° C. compared to Example 1), and A comparative oxygen-doped ScN crystal thin film was obtained in the same manner except that the substrate was heated to 913 ° C.

The produced oxygen-added ScN crystal thin film had an electron concentration of 0.7 × 10 ²¹ (cm ⁻³ ) and a mobility of 181 (cm ² / Vs). The resistivity was 4.7 × 10 ⁻⁵ (Ω · cm), showing the low resistance characteristic shown in the above example, and the half width was 0.1-0.2 °. However, the color was close to gray with low transparency. The oxygen concentration in this thin film is an average value close to 10 ²¹ (cm ⁻³ ), but is very high on the substrate side, decreases toward the surface, and is distributed very unevenly. In the vicinity, the concentration was as low as 10 ¹⁹ (cm ⁻³ ). Furthermore, it was confirmed by photoelectron spectroscopy that a high concentration of defect levels exists in the band gap.
(Comparative Example 6)
In Example 1, the substrate is a sapphire c-plane, and the Sc / N supply ratio is N rich (in comparison with Example 1, the supply temperature is increased by controlling the evaporation temperature of the Sc supply cell by 5 ° C.) In particular, an oxygen-added ScN crystal thin film of a comparative example was obtained in the same manner except that the radical supply source was set to have a very high ion concentration and a low atomic nitrogen concentration.

The color of the produced oxygen-added ScN crystal thin film was yellow-orange with high transparency, but the result of the secondary ion mass spectrometer is as shown in the distribution 3 in FIG. Therefore, it was estimated that the oxygen concentration was very high and it was difficult to determine the oxygen concentration with a secondary ion mass spectrometer, and the concentration was as wide as 10 ²¹ (cm ⁻³ ). However, the electron concentration was 4 × 10 ¹⁹ (cm ⁻³ ), which is about two orders of magnitude lower than the oxygen concentration, and the mobility was a low value of 6 (cm ² / Vs).

The oxygen-doped ScN crystal thin film of the present invention, its manufacturing method, electrode, and electronic device reproduce electrical characteristics with an electron mobility of 90 (cm ² / V · sec) or more and an electron concentration of 1 × 10 ²⁰ (cm ⁻³ ) or more. The present invention relates to an oxygen-added ScN crystal thin film that can be obtained with high performance and can be used as an electrode material.

DESCRIPTION OF SYMBOLS 10 Oxide substrate 10a Top surface of oxide substrate 11 Oxygenated ScN crystal thin film 11a Oxygenated ScN crystal thin film surface 11b Oxidized ScN thin film back surface 7-a p-type layer 7-b active layer 7-c n-type layer 7 -D n-side electrode (oxygenated ScN)
7-e p-side electrode 8-a p-type layer 8-b n-type layer 8-c n-side electrode (oxygenated ScN)
8-d substrate 8-e p-side electrode 8-f anti-reflection coating 8-g wide gap p-type layer

Claims (4)

When an ScN crystal is grown on one surface of an oxide substrate by supplying Sc and atomic nitrogen of purity 99.9% or more by the MBE method, the Sc / N supply ratio becomes 1 or N-rich. The Sc is supplied by controlling the temperature of the supply cell, and the emission line of the plasma is observed through the discharge plasma cell in a state where the emission line in the wavelength region of 750 to 900 nm is observed to be stronger than the emission line in the wavelength region of 250 to 450 nm. A method of forming an oxygen-added ScN crystal thin film , comprising supplying atomic nitrogen and heating the oxide substrate to a temperature range of 902 ° C. to 914 ° C. _{2. The} method for forming an oxygen-added ScN crystal thin film according to claim 1 , wherein the oxide substrate is an MgO substrate or an α-Al ₂ O ₃ substrate. The one surface is any one of MgO (100) surface, MgO (110) surface, α-Al ₂ O ₃ (m surface) and α-Al ₂ O ₃ (r surface). The method for forming an oxygen-added ScN crystal thin film according to any one of 1 and 2 . The oxygen-added ScN crystal according to any one of claims 1 to 3 , wherein a growth rate when forming the ScN crystal thin film is 50 (nm / h) or more and 200 (nm / h) or less. Thin film deposition method.