JPH0738459B2 - Blue light emitting device manufacturing method - Google Patents

Description

The present invention relates to a ZnSySe ₁ -y (0 ≦ y ≦ 1) blue light emitting device having a MIS (Metal-Insulator-Semiconductor) structure.

[Prior art]

The following is a conventional method of manufacturing a MIS type blue light emitting device using a ZnSySe ₁ -y layer as a light emitting layer.

1. Bulk ZnSe or ZnS is subjected to zinc melt treatment to reduce its resistance, and then an insulating layer and a metal electrode are laminated on the open wall surface. (For example Appl.Phys.Let., 27 (1975) 697.Jap
anese J. Appl. Phys., 16 (1977) 77.) 2. MOCV using dialkylzinc and H ₂ S as raw materials on n-Gap
An insulating layer and a metal electrode are laminated on the n-type ZnS layer manufactured by the D method. (For example, Japanese Patent Laid-Open Publication No. Sho 58-165386, Ext.
ended Abstracts of the 15th Conference on Solid St
ate Devices and Materials 1983 pp349 B-7-8) 3. A ZnSe layer is grown on a single crystal substrate by a molecular beam epitaxy method (MBE method) to form a MIS structure or a hetero pn junction. (For example, JP-A-57-18889,
(See Sho-58-21383, Sho-59-11688, Sho-59-16393, Sho-59-172278) [Problems and Objectives to be Solved by the Invention] The above-mentioned prior arts 1 to 3 have the following problems. .

Regarding Conventional Technique 1 Crystal growth of bulk ZnSe and ZnS and zinc melt treatment are batch processes, respectively, and it takes a long time, so mass productivity is poor. (For example, in the iodine transport method using a sealed tube, 7
Approximately about 1 cm ³ of crystals can be formed in 10 days) About Conventional Technique 2 In the MOCVD method using dimethylzinc and H ₂ S on n-GaP, Al-doped ZnS (hereinafter ZnS: Al) was formed, but since the specific resistance in as-grown is extremely high at 10 ⁴ Ω · cm, a MIS type blue light emitting device using this ZnS: Al as a light emitting layer has not been realized. This is because the raw material dimethylzinc is so active that the ZnS fine particles generated by the reaction before the raw material gas reaches the substrate are taken into the growth film, and the crystallinity of the obtained film deteriorates. Is.

Regarding Conventional Technique 3, the MBE method requires an ultrahigh vacuum of 10 ^-9 to 10 ^-11 Torr, and thus the equipment manufacturing cost and maintenance cost are high. Further, since the structure of the apparatus is complicated, it is difficult to increase the size, and the wafer processing capacity per batch is not so large, so that the mass productivity is poor.

Therefore, the present invention solves such a problem, and an object of the present invention is to provide a MIS type blue light emitting element having ZnSySe ₁ -y (0 ≦ y ≦ 1) as a light emitting layer with excellent mass productivity and reproducibility. It is to provide a manufacturing method.

[Means for solving problems]

The method for manufacturing a blue light-emitting device according to the present invention is a method of manufacturing an n-type ZnSySe _1- y (0 ≦ y ≦ on one surface of a substrate by a metal organic vapor phase thermal decomposition method using an adduct containing dialkylzinc as a zinc source.
1) a step of forming a layer, a step of forming an insulating layer on the n-type ZnSySe _1- y layer, and a step of forming an electrode layer on the insulating layer and the other surface of the substrate. Characterize.

In addition, the adduct has the general formula R ₂ Zn—SeR ₂ (R is CnH ₂ n ₊₁
Represents an adduct of dialkylzinc and dialkylselenium.

Further, the adduct, dialkylzinc and dialkylselenium are mixed by excessively mixing low boiling point components of both, and after reaction and aging, dialkylzinc obtained by separating the excessively mixed components is obtained. It is characterized by being an adduct of dialkyl selenium.

Further, the reaction and aging are characterized by being a reaction and aging by a 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.

Adducts of R ₂ Zn and R ₂ Se is a R ₂ Zn as an electron acceptor, one-to-one acid and R ₂ Se as an electron donor - with those resulting from the base reaction R ₂ Zn-SeR _It consists of _two structures. 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 0 ° C for 0.5 to 1 hour.

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

Finally, excess components are separated by distillation.

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 excess component separated 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
While charging and stirring (CH ₃ ) ₂ Zn 58.5 g (0.613 mol)
Was added dropwise with a dropping funnel and reacted. 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. After that, unnecessary excess was separated by distillation. 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.

Further, the adducts shown in Table 2 were obtained through the same steps.

An example of manufacturing a blue light emitting element using an adduct formed by the above-described manufacturing method will be described below.

Example 1 An example of manufacturing a MIS type light emitting device having ZnSe as a light emitting layer is 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. In addition, triethylaluminum (TEAl), which is a source of Al, is enclosed in a bubbler 16. The carrier gas and hydrogen selenide are each in a cylinder.
It is filled in 17,18. The flow rates of the carrier gas and the selenized water surface purified by the purifier 19 are controlled by the mass flow controller 20. The additional body and TEAl enclosed in the bubblers 15 and 16 are maintained at a predetermined temperature by a thermostat 21. A desired amount of the adduct and TEAl are supplied by introducing a suitable amount of carrier gas into the bubbler and performing bubbling. Bubblers 15, 16 and cylinders 18
The supplied adduct and TEAl hydrogen selenide are each diluted with carrier gas and then merged together to form a three-way valve.
It is introduced into the reaction tube 6 via 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.

Low resistance n-type gallium arsenide (GaAs) substrate trichloroethylene sliced and mirror-polished on a (100) plane and a plane having a deviation of 5 ° or 2 ° from the (100) plane to the (110) plane, Perform ultrasonic cleaning with acetone and methanol. Then, etching is performed for 2 minutes at room temperature with an etching solution of H ₂ SO ₄ : H ₂ O ₂ : H ₂ O = 5: 1: 1 (volume ratio). The etching was stopped using pure water, washed with pure water and methanol, and then stored in Die Freon. Immediately before setting the substrate in the reaction tube, the substrate is taken out from the diflon and the diflon is dried and removed by dry nitrogen blowing. After setting the substrate, 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 it to the normal pressure in the system, the temperature rise is started while flowing the carrier gas at about 1 to 2 / min. An infrared heating furnace was used for heating. As carrier gas, purity 99.999
9% He or H ₂ passed through a purifier was used. After the substrate temperature reaches a predetermined temperature and stabilizes, the supply of the source gas is started and the low resistance ZnSe film is grown. As adduct, formed by dimethylzinc and dimethyl selenium _{(CH 3) 2 Zn-Se} (CH 3) was used _2. Under the growth conditions shown below, ZnSe: Al of about 3 μm is formed.

Substrate temperature 200-350 ℃, distance from raw material inlet to substrate 20
cm, bubbling amount of adduct 30 ml / min at -15 ℃, TEAl
Bubbling amount 20 ml / min at -10 ℃, diluted with He 1
% H ₂ Se supply rate, 200 ml / min, total gas flow rate including carrier gas, 4.5 / min, growth time 190 min After forming the ZnSe: Al layer, a ZnSe insulating layer is formed according to the following procedure.

1. By operating the three-way valve 22, the source gas and gas processing system 12
Then, the supply to the reaction tube 6 is interrupted by discarding.

2. Stop the TEAl supply by operating the valve 23 of the bubbler 16.

3. TEAl remaining in the pipe after gas is discarded for a while
To remove. In order to efficiently remove TEAl, the supply of all the raw material gases and the carrier gas may be interrupted, and the exhaust system 11 may evacuate the inside of the piping via the valves 13 and 14.

4. By operating the three-way valve 22, the raw material gas consisting of the adduct and hydrogen sulfide is introduced into the reaction tube 6.

This starts the growth of Andove ZnSe. An undoped ZnSe layer of about 1000 Å is formed by the growth for about 7 minutes.

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. 1% H ₂ diluted with He to prevent thermal etching of the substrate surface
It may be cooled while flowing Se at about 50 to 60 ml / min. When the substrate returns to room temperature, the reaction furnace is evacuated to remove the hydrogen selenide remaining in the system. After returning the system to atmospheric pressure, the substrate is taken out.

As the insulating layer, the additive is used as the zinc source as described above.
In addition to using Andove ZnSe formed by MOCVD method, a thickness of 100 on ZnSe: Al by sputtering or electron beam evaporation.
An insulating film of about 0 to 2000 Å may be laminated. The material is SiO ₂ ,
_{Si 3 N 4, Ta 2 O} 5, Al 2 O 3, ZnS, NaF, good, etc. MgF _2.

Then, an ohmic contact is formed on the back surface of the substrate 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 350-500 ° C for 5-10min. Finally, as a contact electrode on the insulating layer, gold IT again
Form an O layer. 30 Au to ensure light extraction
Set the thickness to about 500Å.

When a forward bias voltage was applied to the device having the MIS structure manufactured as described above, light emission was observed from around 1 to 2V.

The emission intensity increased in proportion to the current flowing through the device. The emission spectrum has a peak at around 475 nm at room temperature,
The luminous efficiency of the device was about 10 ^-3 .

In the above-described embodiment, the following effects, which are not available in the prior art, were obtained.

1. The variation in device characteristics was about 10% when compared in the same wafer or between different batches. It seems that variations in characteristics can be further reduced by improving the device manufacturing process.

2. In the above-mentioned steps, the time required to prepare the ZnSe layer by MOCVD is about 4 hours per batch, and mass production of one digit or more can be expected compared to the bulk crystal growth in the conventional method.

3. With respect to the processing capacity per wafer batch, the number of processed wafers and the diameter can be increased depending on the size and shape of the reaction tube.

As can be easily inferred from the above examples, similarly to the addition of Al to ZnSe, the addition of Ga and In also corresponds to the corresponding organometallic compounds such as triethylgallium (boiling point = 143 ° C.) and triethylindium (boiling point = 184 ° C.). C.) is possible. When the supply amount calculated from the vapor pressure at the bubbling temperature and the flow rate of the bowling gas is equal to that of triethylaluminum, the MIS type blue light emitting device having ZnSe: Ga, ZnSe: In as the light emitting layer also has ZnSe: Al as the light emitting layer. It showed similar characteristics to those of

By introducing an organic compound containing chlorine, hydrogen chloride, or a halogen element instead of the group III element organometallic compound during the ZnSe growth in the above-mentioned examples, ZnSe: X exhibiting the same electrical characteristics as ZnSe: Al. A single crystal thin film of (X = Cl, Br, I) can be manufactured. A MIS type blue light emitting device using this as a light emitting layer could be manufactured. The characteristics of the obtained device are ZnSe: A
It was the same as the device using l as the light emitting layer.

In this example, an adduct obtained from (CH ₃ ) ₂ Zn and (CH ₃ ) ₂ Se was used, but the adducts shown in Table 2 and other adducts formed in the same manner are used. As for the zinc source, when the supply amount and manufacturing conditions were the same as those of this example, a semiconductor device having similar characteristics was obtained.

Example 2 In Example 1, by using hydrogen sulfide as a group VI source instead of hydrogen selenide, ZnS: X (X = Al,
A MIS type blue light emitting device having a light emitting layer of Ga, In, Cl, Br, I) can be manufactured. At this time, in FIG. 2, hydrogen sulfide is supplied as a He-base 2% gas from the gas cylinder 24, and the flow rate is controlled by the mass flow controller 20 before the reaction tube 6
Be introduced to. At a growth temperature of 350 ° C. or lower, the decomposition rate of alkyl selenium is extremely low, so the incorporation of selenium into ZnS: X can be ignored.

ZnS: X was applied to a low-resistivity n-type gallium arsenide (GaAs), gallium phosphide (GaP) or silicon (Si) substrate treated in the same manner as in [Example 1] in the same manner as in [Example 1]. Grow. The substrate etching conditions and ZnS: X growth conditions are as follows.

Etching conditions GaP substrate HCl: HNO ₃ = 3: 1 (volume ratio) at room temperature for 30 seconds Si substrate HF: H ₂ O = 1: 1 (volume ratio) at room temperature for 2 min Growth conditions Substrate temperature 250-350 ℃, from raw material inlet Distance to board 20
cm, bubbling amount of adduct 30 ml / min at -15 ℃, TEAl
Bubbling amount-20 ml / min at -10 ℃, diluted with He 2
% H ₂ S supply rate 100 ml / min, total gas flow rate including carrier gas 4.5 / min, growth time 190 min Under the above growth conditions, a ZnS: A layer of about 3 μm can be formed. Similarly, ZnS: X can be changed by changing the type of dopant.
(X = Ga, In, Cl, Br, I) can be formed.

Then, by performing the same post-process as in [Example 1], MI
An S-type light emitting device can be manufactured. The conditions for forming the ohmic contact with the GaP substrate and the Si substrate are as follows.

GaP Substrate Au-Si (Si = 2wt-%) is vapor-deposited at about 2000Å and then heat-treated in an inert atmosphere at 400-600 ℃ for 5-10min Si substrate Al or Al-Si (Si = 2wt-%) is about 3000Å The MIS type light emitting device manufactured by sputtering or vapor deposition and heat treatment at 300 ° C. for 30 minutes in an inert atmosphere exhibited blue light emission having a peak in the vicinity of 470 to 475 nm when a forward bias voltage of about several V was applied. The EL spectrum was broader than that of the device using ZnSe: X as the light emitting layer. A typical example of the emission spectrum is shown in FIG. 3, and the emission efficiency of the device was about 10 ⁻⁴ to 10 ⁻³ . Also, in this example, the same effect as in [Example 1] was obtained.

[Example 3] Similar to [Examples 1 and 2], ZnSySe ₁ -y: X (0 <y <was obtained by using hydrogen selenide and hydrogen sulfide as the group VI source.
1) A MIS type blue light emitting device having a light emitting layer of (X = Al, Ga, In, Cl, Br, I) can be manufactured. The composition of selenium and sulfur can be arbitrarily changed depending on the supply amount ratio. Figure 4 shows the gas composition of ZnSy.
It shows a correlation with the solid phase composition ratio of Se ₁ -y.

The produced MIS type element showed the same characteristics as the element produced in [Example 1] or [Example 2]. Also, in this example, the same effect as in [Example 1] was obtained.

〔The invention's effect〕

As described above, n-other ZnSy is produced by the organometallic vapor phase pyrolysis method using an adduct containing dialkylzinc as a zinc source.
By forming the Se _1- y (0 ≦ y ≦ 1) layer, it became possible to manufacture the MIS type blue light emitting device with excellent mass productivity and reproducibility.

We are convinced that the present invention greatly contributes to manufacturing a display using a visible light emitting diode.

[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 Figure 2 is a schematic view 6 ...... quartz glass reaction tube of the MOCVD apparatus used in the present invention, 7 graphite susceptor subjected to ...... SiC coating, 8 …… Substrate, 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 ... … Bubblers containing dopants such as triethylaluminum, 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 Fig. 3 shows the emission spectrum of the blue light emitting device manufactured in the present invention. FIG. 4 is a correlation diagram of the gas composition and the obtained crystal composition when forming the ZnSySe ₁ -y layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norihisa Okamoto 3-3-5 Yamato, Suwa City, Nagano Prefecture Suwa Seikosha Co., Ltd. (56) Reference JP-A-58-165386 (JP, A) 58-218181 (JP, A)

Claims (4)

[Claims] 1. An n-type ZnSySe _1- y (0 ≦ y ≦ 1) layer is formed on one surface of a substrate by a metal organic vapor phase pyrolysis method using an adduct containing dialkylzinc as a zinc source. A step of forming an insulating layer on the n-type ZnSySe _1- y layer, a step of forming an electrode layer on the insulating layer and the other surface of the substrate; Manufacturing method. 2. The adduct has the general formula R ₂ Zn—SeR ₂ (R is Cn
The method for producing a blue light-emitting device according to claim 1, which is an adduct of dialkylzinc and dialkylselenium represented by H ₂ n ₊₁ ). 3. The adduct is obtained by diluting dialkylzinc and dialkylselenium in excess of low-boiling components, reacting and aging, and separating the excessively mixed components. The method for producing a blue light emitting device according to claim 2, which is an adduct of dialkylzinc and dialkylselenium. 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 blue light emitting element according to claim 3, wherein