JPH0695580B2 - Manufacturing method of semiconductor light emitting device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor light emitting device that emits blue light.

[Outline of Invention]

The present invention is applicable to n-type ZnSySe ₁ -y (0 ≦ y ≦ 1) and P-type ZnSyS.
Metal-organic vapor phase pyrolysis method using a dialkylzinc-containing adduct as a zinc source in a method of manufacturing a semiconductor light-emitting device that exhibits blue light emission using a P-n junction formed by e ₁ -y (0 ≦ y ≦ 1) N-type or P depending on (MOCVD method)
By forming the −-type ZnSySe ₁ -y layer, it is possible to mass-produce semiconductor devices that emit blue light.

[Conventional technology]

An outline of a semiconductor light emitting device that emits blue light, which has been reported or put into practical use, is described below.

1. A light emitting device having a P-n junction formed by diffusing a dopant into a bulk ZnSe single crystal. (For example, J.Appl.Phy
s., 57 , (1985) 2210. Japanese Patent Laid-Open Publication No. 59-6583. 2. A light emitting device having a Pn junction formed by diffusing a dopant into a bulk ZnSySe1-y single crystal. (For example, Appl.P
hys. Lett., 27 (1975) 74.) 3. A light emitting device having a MIS structure in which an insulating layer and an electrode layer are laminated on a bulk n-type ZnSySe ₁ -y single crystal. (For example, Appl.Ph
ys.Lett., 27 (1975) 697.Japan.J.Appl.Phys., 13 (197
4) 357.Japan.J.Appl.Phys., 16 (1977) 77.) 4. A light emitting device having an MIS structure in which an insulating layer and an electrode layer are laminated on n-type GaN. (See, for example, Nikkei Electronics May 11, 1981, p. 82.) 5. Light emitting device using SiC P-n junction. (See, for example, Nikkei Electronics May 28, 1979 issue P.111.) [Purpose of Invention] The above-mentioned prior art has the following problems.

I. Prior arts 1 and 2 ... Bulk production, which is said to be extremely difficult to increase in size at present, is used as a starting material, and the dopant diffusion process is performed by batch processing in a closed system. Therefore, mass productivity and process reproducibility are poor. .

B. Prior art 3 and 4 ... The light emitting device has a MIS structure, and light is emitted by recombination of minority carriers injected through an insulating layer. In principle, the light emission efficiency is lower than in the prior arts 1 and 2 in which light is recombined to emit light.

C. Conventional technology 5 ... Since SiC is an indirect transition type semiconductor, it is difficult to improve luminous efficiency, and mass production is poor because a large-diameter substrate of SiC cannot be obtained.

Therefore, in the present invention, the above-mentioned problems in the prior art are solved, and the purpose thereof is to use a ZnSySe ₁₁ y, which is a direct transition type semiconductor that can be expected to have high luminous efficiency, to form a P-n junction. The semiconductor light-emitting device has a large-diameter substrate of good quality, and on GaAs, GaP, Si, etc., it is possible to obtain dialkylzinc and dialkylselenium, which are excellent in mass productivity and controllability of crystal growth, and which can obtain a good quality epitaxial film. A semiconductor light emitting device that emits blue light is manufactured by a MOCVD method using an organic zinc compound that is an adduct as a zinc source.

[Means for solving problems]

Preparation of a semiconductor light-emitting device according to the present invention, by metal organic vapor phase pyrolysis method using adduct containing dialkyl zinc and zinc source, n- type ZnSySe _1- y and p- type ZnSySe _1- y layer (0 ≦
y ≦ 1) is formed.

Further, as the adduct, a compound represented by the general formula R ₂ Zn—SeR ₂ (R = Cn
It is characterized by using an adduct of dialkylzinc and dialkylselenium represented by H ₂ n ₊₁ ).

Further, as the adduct, dialkylzinc and dialkylselenium are mixed in excess with each other in an amount of a low-boiling point component, reacted and aged, and then the dialkylzinc obtained by separating the excessively mixed component is obtained. It is characterized by using an adduct of dialkyl selenium.

Further, the reaction and aging are characterized by being a reaction and aging by heat treatment including a step of holding at 0 ° C to 40 ° C, a step of gradually raising the temperature, and then a step of holding at 30 ° C to 80 ° C. To do.

〔Example〕

A method for producing an organozinc compound composed of an adduct used in the present invention will be described.

The adduct of dialkylzinc (R ₂ Zn) and dialkylselenium (R ₂ Se) was obtained as a result of a one-to-one acid-base reaction between R ₂ Zn as an electron acceptor and R ₂ Se as an electron donor. It has a structure of R ₂ Zn-SeR ₂ . The following steps are required for producing the adduct.

R ₂ Zn and R ₂ Se, the low boiling point component of both is generally in excess,
Preferably, the ratio of low boiling point component to high boiling point component is 1.05-1.
They are mixed at a ratio of 2 equivalents, and both are mixed at a boiling point of a low-boiling point component or less at about 0 ° C to 40 ° C for 10 minutes to 3 hours, preferably 10 to 35
Sufficiently react at 30 ° C for 1 minute to 1 hour.

After that, to complete the reaction, gradually raise the temperature to 30-80 ° C.
The temperature is raised for 10 minutes to 2 hours, preferably 10 to 15 ° C./hour, and aged at 30 to 70 ° C. for 30 minutes to 1 hour.

Finally, excess components are distilled off, ie separated.

The formation of the adduct can be confirmed by the following facts.

(1) Heat is generated by mixing the two.

(2) The vapor pressure-temperature curve of the produced adduct is different from that of R ₂ Zn and R ₂ Se which are the starting materials.

(3) the remaining amount obtained by subtracting the separated distillate excess components by distillation from the charged amounts of the raw materials is R ₂ Zn and R ₂ S 1: match the weight was assumed to form the adduct with 1.

Specific examples (CH _{3) 2} Zn and (CH _{3) 2} Se consisting adduct _{(CH 3) 2 Zn-Se} (CH 3) 2 will be described.

63.5 g (0.583 mol) of (CH ₃ ) ₂ Se in a 300 ml round bottom flask
After charging, with stirring, 58.5 g (0.613 mol) of (CH ₃ ) ₂ Zn was added dropwise with a dropping funnel to react. The reaction was exothermic and the exotherm was large.

The reaction temperature was controlled at 8 to 15 ° C and the reaction was carried out for 40 minutes. Thereafter, the temperature was gradually raised at a rate of 15 ° C./hour and aging was carried out at 45 ° C. for 1 hour. Thereafter, unnecessary excess was distilled off by distillation, that is, separated. The product was 118 g.

FIG. 1 shows the vapor pressure-temperature characteristics of the obtained adduct. The horizontal axis 1 is temperature and the vertical axis 2 is vapor pressure.

The solid line 3 is the adduct, and the broken lines 4 and 5 are the raw material Se (C
₂ shows vapor pressure characteristics of H ₃ ) ₂ and (CH ₃ ) ₂ Zn.

Table 1 shows vapor pressure values at typical temperatures.

Moreover, the adduct shown in Table 2 was obtained by going through the same steps.

An example of manufacturing a semiconductor light emitting device by the MOCVD method using the additional body formed by the above manufacturing method will be shown below.

FIG. 2 is a schematic diagram of the MOCVD apparatus used in the present invention.

Inside a horizontal reaction tube 6 made of quartz glass, a graphite susceptor 7 coated with SiC is placed, and a substrate 8 is placed thereon. The substrate is heated from the side surface of the reaction furnace by a high-frequency heating furnace, an infrared furnace, a resistance heating furnace 9, or the like. The substrate temperature is monitored by a thermocouple 10 embedded in the graphite susceptor 7.
The reaction tube is connected to the exhaust system 11 and the waste gas treatment system 12 via valves 13 and 14. The Zn source adduct is enclosed in a bubbler 15. A bubbler 16 is filled with an organic metal compound containing a group III element or an organic compound containing a halogen element, which is a source of the n-type dopant. Carrier gas, hydrogen selenium (H ₂ Se) and hydrogen sulphate (H ₂ S) are filled in cylinders 17, 18 and 24, respectively. The flow rates of the carrier gas, hydrogen selenide, and hydrogen sulfide purified by the purifier 19 are controlled by the mass flow controller 20. The adduct and the n-type dopant enclosed in the bubblers 15 and 16 are maintained at a predetermined temperature by the thermostatic bath 21.
A desired amount of the adduct and the n-type dopant are supplied by introducing an appropriate amount of carrier gas into the bubbler and performing bubbling. Gases such as chlorine, hydrogen chloride, hydrogen bromide and hydrogen iodide, which are n-type dopants, are supplied to the cylinder 25, and ammonia, hydrogen phosphide, hydrogen arsenide and the like, which are P-type dopants, are supplied to the cylinder 26. Each gas is filled in a state diluted with hydrogen gas. The flow rate of the dopant gas is controlled by the mass flow controller 20.
The adduct, hydrogen selenium, hydrogen sulfide, and the dopants supplied as described above are diluted with the carrier gas, then merged, and introduced into the reaction tube 6 through the three-way valve 22. The three-way valve 22 switches the introduction of the raw material gas to the reaction tube 6 and the disposal to the waste gas treatment system 12. Although a horizontal reactor is shown in FIG. 2, the basic structure is the same in a vertical reactor. However, it is necessary to ensure the uniformity of the film obtained by providing the rotation mechanism of the substrate.

The epitaxial growth of ZnSySe ₁ -y (0 ≦ y ≦ 1) on the substrate is performed as follows. The cleaned and etched substrate is set in the reaction furnace. After that, the inside of the reaction furnace is evacuated to about 10 ^-5 Torr to remove the gas remaining in the system. After introducing the carrier gas and returning the system to normal pressure, the temperature rise is started while flowing the carrier gas at about 1 / min / min. Hydrogen or helium was used as the carrier gas. After the substrate temperature reaches a predetermined temperature and becomes stable, the supply of raw material gas is started to grow ZnSySe ₁ -y. After growing for a predetermined time, the supply of the raw material is stopped and the material is cooled. He or H ₂ is allowed to flow at 1 to 2 / min during cooling. In order to prevent thermal etching of the substrate surface, hydrogen selenide or hydrogen sulfide may be cooled while flowing about 50 to 60 ml / min. When the substrate returns to room temperature, the reaction furnace is evacuated to remove the hydrogen sulfide remaining in the system. After returning the system to atmospheric pressure, the substrate is taken out.

By performing crystal growth using the MOCVD apparatus shown in FIG. 2 according to the above steps, n-type ZnSySe ₁ -y, P-type Z
An epitaxial film of nSySe ₁ -y can be formed.

[Example 1] Fabrication of semiconductor light emitting device having ZnSe P-n junction (100) plane of n-type gallium arsenide (GaAs), 5 ° or 2 ° from (100) plane to (110) plane. A semiconductor light emitting device is manufactured on the misaligned surface according to the following steps.

1. Formation of n-type ZnSe Substrate temperature: 200-350 ° C (CH ₃ ) ₂ Zn-Se (CH ₃ ) ₂ bubbling gas flow rate of the adduct: Dilute with 30 ml / min H ₂ at bubbler temperature of -15 ° C Supply rate of 2% H ₂ Se: 200ml / min Bubbling gas flow rate of triethylaluminum (TEAl): 10-30ml / min at bubbler temperature -10 ℃ Total gas flow rate including carrier gas: 4.5 / min Growth time: 200min or more Under conditions of about 3 μm n-type ZnSe on GaAs
The layer can be grown epitaxially. The specific resistance of the film is 0.5-1
It was about 0 Ω · cm.

2. Formation of P-type ZnSe After the formation of the n-type ZnSe layer is completed, the supply of the reaction gas to the reaction furnace is interrupted by operating the three-way valve 22. Then, the supply of TEAl which is an n-type dopant is stopped, and the supply of NH ₃ which is a P-type dopant is started. The reaction gas is discarded for a while, and after the flow rate is stabilized, the three-way valve 22 is operated again to introduce the reaction gas into the reaction furnace. A P-type ZnSe layer is laminated on the n-type ZnSe layer. The growth conditions are as follows.

The supply amount of 5% NH ₃ was diluted with H _2: 5~50ml / min Growth Time: 200 min Other conditions are the same as the conditions for forming the n- type ZnSe.

At this time, a P-type ZnSe layer having a thickness of about 3 μm can be epitaxially grown. The specific resistance of the film was about 10 to 150 Ω · cm.

3. Formation of ohmic contact An ohmic contact is formed under the following conditions.

GaAs substrate Au-Ge (Ge = 12wt-%) or Au-Sn is vapor-deposited at about 2000Å and then heat-treated in an inert atmosphere at 250-400 ° C for 5-10 min. P- type ZnSe layer a. Au, In, Zn, About 1000Å is deposited.

B. Apply conductive silver paste.

C. In-Ga, In-Hg is attached to the surface and 300
Heat treatment at ˜400 ° C. for about 5 minutes After cutting the light emitting device having a P-n junction formed through the above steps into a chip of about 200 μm × 200 μm,
When leads are taken out from the P-layer side and the gaAs substrate side and a forward bias is applied, blue light emission is obtained. Luminous intensity increases with current, and the luminous brightness at 20mA is about 2
It was 3 millicandela.

A typical emission spectrum is shown in FIG. The peak wavelength of the emission spectrum was located at about 475 to 485 nm at room temperature, and the full width at half maximum was about 10 nm. The luminescent color was pure blue to the naked eye. In this example, the following effects were obtained.

1. The variations in the emission wavelength, the emission threshold voltage, and the current of the light emitting device manufactured from the same wafer were about 10% on average.

2. The variation in the characteristics of the light emitting device manufactured from different wafers or wafers with P-n junctions formed in different batches is
It was about 15 to 20%.

As described above, the light emitting device with less variation can be mass-produced in this embodiment. In this example, the light emitting device was manufactured on a wafer having a diameter of about 1 inch.
By changing the size and shape of the reaction furnace, it is possible to process a plurality of wafers having a larger diameter. By the way, the time required for the manufacturing process is about 8 hours for the growth process of ZnSe and about 5 hours for the subsequent processes. It is self-evident that the mass productivity is significantly improved as compared with the conventional technique of handling a bulk crystal in a closed system.

Example 2 A method for manufacturing a semiconductor light emitting device having a ZnSySe ₁ -y (0 <y ≦ 1) Pn junction.

n-type gallium arsenide (GaAs), gallium phosphide (Ga
P), Silicon (Si), Germanium (Ge) (100)
A semiconductor light emitting device is manufactured according to the following steps on a plane having a deviation of 5 ° or 2 ° in the direction from the (100) plane to the (110) plane.

1. Formation of n-type ZnSySe ₁ -y Substrate: 200 to 350 ° C (CH ₃ ) ₂ Zn-Se (CH ₃ ) ₂ bubbling gas flow rate of the adduct: bubbler temperature -15 ° C at 30 ml / min H ₂ the supply amount of 2% H ₂ Se diluted: 0~200ml / min H supply amount of diluted 2% H ₂ S in _{2: 0~200ml} / min bubbling gas flow rate of triethylaluminum (TEAl): bubbler temperature -10 ° C. Total gas flow rate including carrier gas at 10 to 30 ml / min: 4.5 / min Growth time: 200 min In order to change the solid phase composition ratio y of ZnSySe ₁ -y, H ₂ Se and H ₂ S in the source gas should be changed. The composition ratio may be changed. Fourth
The figure shows the correlation between the gas composition and the solid-phase composition ratio of ZnSySe ₁ -y.
In order to improve the crystallinity of epitaxially grown ZnSySe ₁ -y, it is desirable to select a solid-phase composition that is lattice-matched with the substrate. Table 3 shows the types of substrates and the composition ratios of H ₂ Se and H ₂ S for growing ZnSySe ₁ -y that has a lattice match with the substrates used.

Under the above conditions, an n-type ZnSySe ₁ -y layer of about 3 μm can be epitaxially grown. The specific resistance of the film is 0.5 to 20Ω
・ It was about cm.

2. Formation of P-type ZnSe After the formation of the n-type ZnSySe ₁ -y layer is completed, the supply of the reaction gas to the reaction furnace is interrupted by operating the three-way valve 22. continue,
discontinue the supply of TEAl a n- type dopant starts supply of NH ₃ is p- type dopant. For a while,
Three-way valve again after discarding the reaction gas and stabilizing the flow rate
22 is operated to introduce the reaction gas into the reaction furnace. n-type ZnSy
A P-type ZnSySe ₁ -y layer is laminated on the Se ₁ -y layer. The growth conditions are as follows.

The supply amount of 5% NH ₃ was diluted with H _2: 5~50ml / min Growth Time: 200 min Other conditions are the same as the conditions for forming the n- type ZnSySe _1- y P- type in this case a thickness of about μm ZnSySe _1- y layer can be grown epitaxially. The specific resistance of the film was about 15 to 200 Ω · cm.

3. Formation of ohmic contact An ohmic contact is formed under the following conditions.

GaP substrate Au-Si (Si = 2%) or Au-Sn is vapor-deposited at about 2000Å, then heat-treated at 500-600 ℃ for 5 minutes in an inert atmosphere Si, Ge substrate Al or Al-Si (Si = 2%) 3000Å Sputtering or vapor deposition, heat treatment at 300 ° C. for 30 minutes in an inert atmosphere P-type ZnSySe ₁ -y layer b. Au, In, Zn, etc. are vapor deposited at about 1000Å.

B. Apply conductive silver paste.

C. In-Ga, In-Hg is attached to the surface and 300
Heat treatment at ~ 400 ° C for about 5 minutes After cutting the light emitting device having a P-n junction formed through the above steps into a chip of about 200 µm x 200 µm,
-When leads are taken out from the layer side and the GaAs substrate side and a forward bias is applied, blue light emission is obtained. The emission intensity increases with the current, and the emission brightness at 25 mA is about 2 to 2.
It was 5 millicandela.

The peak wavelength of the emission spectrum changed according to the composition of ZnSySe ₁ -y, and shifted to the short wavelength side as y increased. The full width at half maximum was about 10 nm.

Also in this example, the same effect as that of [Example 1] was obtained.

[Example 3] In Examples 1 and 2, TEAl was used as the n-type dopant, but as can be easily analogized, the addition of Ga and In also corresponds to the addition of Al to ZnSySe ₁ -y. It is possible by using an organometallic compound such as triethylgallium (boiling point = 143 ° C.) and triethylindium (boiling point = 184 ° C.). In addition, as the n-type dopant, chlorine, hydrogen chloride, hydrogen bromide, hydrogen iodide, or an organic compound containing a halogen element, such as 1.4-dichlorobutane, propyl bromide, or methylene iodide, can be used. N- using a halogen element as a donor as in the above-described embodiment
A type ZnSySe ₁ -y can be formed.

In addition to NH ₃ , PH ₃ AsH ₃ or the like can be used as the P-type dopant.

The light emitting device manufactured by using the above dopants showed the same characteristics as those obtained in Example 1 or 2 when the doping amount was about the same as those in Examples 1 and 2.

Furthermore, regarding the adduct as a zinc source, Example 1,
Was used in _{2 (CH 3) 2 Zn-} Se (CH 3) 2 in addition to it is possible to use three types of adducts listed in Table 2. The supply amount of the adduct is given under the bubbling conditions in Examples 1 and 2 (C
_{H 3) 2 ZnSe (CH 3} ) at the same time as the _second supply amount, ZnSe and ZnSy
The growth rate of Se ₁ -y was the same, and the characteristics of the obtained light emitting device were at the same level.

In addition, as can be easily analogized, a light emitting device using ZnSe and Zn as a growth substrate and a Pn junction formed by a layer of ZnSySe ₁ -y (0 ≦ y ≦ 1) on the growth substrate is also available. It can be manufactured.

〔The invention's effect〕

As described above, according to the present invention, n-type ZnSySe ₁ -y
(0 ≦ y ≦ 1) and a P-type ZnSySe ₁ -y (0 ≦ y ≦ 1) P-n junction utilizing a Pn junction. Metalorganic vapor phase pyrolysis using zinc source (MOCVD
Method), the n-type or P-type ZnSySe ₁ -y layer can be formed to stably mass-produce semiconductor devices that emit blue light. We believe that the present invention is extremely large in that it contributes to the manufacture of semiconductor devices exhibiting blue light emission and the spread of various devices using them.

[Brief description of drawings]

Figure 1 is _{(CH 3) 2 Zn-Se} (CH 3) 2 vapor pressure - temperature characteristic diagram 1 ...... temperature, 2 ...... vapor pressure, 3 ...... adduct 4 ...... Se (CH
₃ ) ₂ , 5 ... Zn (CH ₃ ) ₂ Fig. 2 is a schematic diagram of the MOCVD apparatus used in the present invention 6 ...... Quartz glass reaction tube, 7 ... SiC coated graphite susceptor, 8 ... Board, 9 ...
High-frequency heating furnace or infrared furnace or resistance heating furnace, 10 ... Thermocouple, 11 ... Exhaust system, 12 ... Waste gas treatment system, 13, 14 ... Valve, 15 ... Bubbler with additional body, 16 ... … Bubber containing n-type dopant, 17 …… Cylinder containing carrier gas 18 …… Cylinder containing hydrogen selenide 19 …… Gas purifier, 20 …… Mass flow controller, 21 …… Constant temperature bath, 22 ...... Three-way valve, 23 …… Valve, 24 …… Cylinder containing hydrogen sulfide, 25 …… Cylinder containing n-type dopant gas 26 …… Cylinder containing P-type dopant gas Fig. 3 The emission spectrum of the semiconductor light-emitting device produced by the manufacturing method concerning this invention. FIG. 4 is a correlation diagram between the gas composition and the obtained crystal composition when the ZnSySe ₁ -y layer is formed.

Claims (4)

[Claims] 1. An n-type ZnSySe _1- y is obtained by a metalorganic vapor phase thermal decomposition method using an adduct containing dialkylzinc as a zinc source.
And a p-type ZnSySe _1- y layer (0 ≦ y ≦ 1) is formed. 2. The adduct of the general formula R ₂ Zn—SeR ₂ (R
The manufacturing method of the semiconductor light emitting device according to claim 1, wherein an adduct of dialkylzinc and dialkylselenium represented by the formula: = CnH ₂ n ₊₁ ) is used. 3. As the adduct, dialkylzinc and dialkylselenium are obtained by excessively mixing low boiling point components of both, reacting and aging, and then separating the excessively mixed components. The method for producing a semiconductor light emitting device according to claim 2, wherein an adduct of dialkylzinc and dialkylselenium is used. 4. The reaction and aging are the reaction and aging by heat treatment including a step of holding at 0 ° C. to 40 ° C., a step of gradually raising the temperature, and then a step of holding at 30 ° C. to 80 ° C. The method for manufacturing a semiconductor light emitting device according to claim 3, wherein