JPH08227902A - Deposition of ii-vi compound semiconductor - Google Patents

Abstract

PURPOSE: To deposit a thin film excellent in crystallinity and orientation while doping a halogen element with high controllability by introducing chemical species containing a halogen element into an atmosphere for depositing a II-VI compound semiconductor. CONSTITUTION: When a II-VI compound semiconductor is deposited by MOCVD, chemical species containing a halogen element is introduced into the atmosphere for depositing the II-VI compound semiconductor. The halogen element can be introduced by any one of following methods. (a). HCL, HBr, HI or CL2 gas diluted with a carrier gas is fed from a cylinder 10. (b). Vapor of volatile liquid, e.g. HBr, HI, Br2 , Cl2 , encapsulated in the cylinder 10 is diluted and fed into a reaction chamber. (c). An liquid organic compound containing a halogen element encapsulated in a bubbler 15 and a carrier gas are bubbled and fed as a gas. (d). Solid state iodine is fed into the bubbler 15 and heated to produce sublimated iodine which is carried on the carrier gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-speed electron
The present invention relates to a method for producing a II-VI group compound semiconductor thin film containing a halogen element used in T, electroluminescence panels and light emitting diodes. More specifically, it relates to a halogen element doping method when forming a II-VI group compound semiconductor thin film by the MOCVD method.

[0002]

2. Description of the Related Art Conventionally containing a halogen element
The method for producing the II-VI group compound semiconductor thin film includes vacuum vapor deposition, electron beam vapor deposition, and sputtering. That is, II-VI compounds such as zinc sulfide (ZnS) and zinc selenide (ZnS
e) a deposition pellet or target prepared by adding an appropriate amount of an impurity such as zinc halide (ZnX ₂ : X = Cl, Br, I) to a high purity powder of zinc telluride (ZnTe). This is the formation of all thin films.

Other Technical Reports ED84-73, ED84
As described in -74, there is also a method of introducing a halogen element by heat diffusion after forming a base thin film.

[0004]

The above-mentioned conventional method has the following problems.

1. Since a thin film obtained by vapor deposition or sputtering is inferior in crystallinity and orientation, light emission efficiency due to photoexcitation of the thin film and light emission efficiency due to minority carrier injection during device fabrication are low.

2. Poor control over the impurity concentration and its distribution.

Such a problem is an inherent problem in a thin film forming method such as vapor deposition or sputtering, and as long as a thin film is formed by vapor deposition or sputtering, a significant improvement in characteristics 1 and 2 cannot be expected. In the method of introducing halogen by diffusion, two problems are particularly serious.

Therefore, the present invention solves such a problem, and an object of the present invention is to prepare a thin film having excellent crystallinity and orientation, and an MO which is excellent in controllability of doping.
It is to prepare a II-VI group compound semiconductor thin film containing a halogen element by using the CVD method.

[0009]

In the method for producing a II-VI group compound semiconductor thin film containing a halogen element according to the present invention,
II-VI by the vapor phase pyrolysis method (MOCVD method) of organic metal
When forming a group compound semiconductor thin film, a chemical species containing a halogen element is introduced into the thin film forming atmosphere.

[0010]

FIG. 1 shows an MOCV used in the present invention.
The schematic diagram of D device is shown. A susceptor 2 made of graphite with SiC coating is set inside a reaction tube 1 made of transparent quartz, and a substrate 3 is placed on the susceptor 2.
Is set. Inside the susceptor 2, a thermocouple 4
The tip of the substrate is embedded to monitor the substrate temperature. A heating furnace 5 made of resistance heating, high frequency wave, infrared ray, or the like is provided around the reaction tube 1 to heat the substrate. Reaction tube 1
Are connected to a waste gas treatment system 8 and an exhaust system 9 via valves 6 and 7, respectively. Cylinders 10, 11, 1
2 includes doping gas, hydrogen sulfide (H ₂ S),
Carrier gas is respectively enclosed. The carrier gas is used after being purified by the purifying device 13. The carrier gas may be either H ₂ or He. Bubbler 14,
15 respectively contain a zinc source and a dopant. Reference numeral 16 denotes a mass flow controller which controls gas flow. The raw materials and the dopants supplied from the cylinders 10 and 11 and the bubblers 14 and 15 are diluted by the carrier gas flowing in 18. The valve 19 is a three-way valve that switches each gas between a reaction tube introduction line 20 and a bypass line 21. The bypass line 21 is led to the gas processing system 8.

(Example 1) Using the above-mentioned MOCVD apparatus, a zinc sulfide (ZnS) single crystal film containing a halogen element was grown on a GaAs, GaP or Si substrate. The following shows the growth process.

1. Cleaning of the surface of the substrate by thermal etching
The aAs, GaP, and Si substrates are set in the reaction tube 1 and the system is evacuated. Subsequently, a carrier gas is introduced and the chamber is evacuated again. This operation removes residual oxygen and residual moisture in the system. While flowing a carrier gas at a rate of about 1 to 2 liters per minute, in the case of a GaAs or GaP substrate, 500 ° C.
It is heated to 600 ° C. and 900 ° C. to 1000 ° C. for a Si substrate. By this thermal etching, the oxide film remaining on the substrate surface can be removed. After performing thermal etching for 5 to 10 minutes, the substrate temperature is set to the growth temperature.

2. Crystal growth H ₂ S is supplied from the bomb 11 to the reaction furnace 1. The doping and zinc source lines are connected to the bypass line 20 by operating the three-way valve 19. Bubbling of the valve 14 by the carrier gas is started, and supply of the zinc source is started. Subsequently, the supply of the dopant is started by gas supply from the cylinder 10 or bubbling of the bubbler 15 by the carrier gas. The H ₂ S, zinc source, and dopant are diluted to a predetermined concentration by the dilution line 18. When the indicated value of the mass flow controller 16 is stabilized, the three-way valve 19 is switched to the reactor 1 and
A source gas and a dopant are introduced into the reactor 1. ZnS: X (X = Cl, Br, I) grows on the substrate.

Typical growth conditions are as follows.

Carrier gas (He): total flow rate 4.5 liters / min Zinc source: 0 ° C bubbling amount of adduct by equimolar mixing of diethyl zinc-diethyl sulfur = 100 ml / min dimethyl zinc-diethyl sulfur equimolar mixture Bubbling amount of adduct by -20 ° C. = 15 ml / min He or H ₂ base 2% H ₂ S supply amount = 100 ml /
min Growth temperature 300 ° C. to 500 ° C. (The adduct in the present invention includes not only an adduct obtained by equimolar mixing of dialkylzinc and dialkylsulfur or dialkylselenium, but also a mixture obtained by equimolar mixing. Further, in the mixture, a part of the mixture forms an adduct and the other coexists in a dissociated state.) Under the above conditions, regardless of the growth temperature and the type of the growth substrate,
The growth rate was almost constant at 0.8 to 10 μm / hr. The growth rate was the same even when the halogen element was doped.

The halogen element can be introduced by any of the following methods.

A. HCl, H diluted with carrier gas
A gas such as Br, HI, Cl _{2 is} supplied from the cylinder 10.

B. The volatile liquid HBr, HI, Br ₂ , and Cl ₂ vapors sealed in the cylinder 10 are diluted and supplied to the reaction furnace.

(C) A liquid organic substance (eg, dichlorobutane, chlorobenzene, dibumompropane, methylene iodide, etc.) containing a halogen element enclosed in the bubbler 15 is vaporized and supplied by bubbling a carrier gas.

D. Solid iodine is placed in a bubbler, and the iodine sublimated by heating the bubbler is transported by a carrier gas.

After the growth for a predetermined time, the gas in the line supplying the zinc source and the halogen element source is switched to the bypass line 21 by operating the three-way valve 19 and discarded. The substrate is cooled to room temperature while flowing 2% H ₂ S diluted with a carrier gas at about 10 to 20 cc / min. Supply of zinc source and halogen element source is stopped. After the substrate is cooled, H ₂ S is switched to the bypass line 21 by operating the three-way valve, then the supply of H ₂ S is interrupted and the inside of the reaction furnace is degassed to remove the residual H ₂ S. By introducing the carrier gas, the inside of the reaction furnace is returned to normal pressure, and the substrate is taken out.

As a typical doping example performed according to the above process, introducing Zn or He ₂ based 1% HCl into a 10-50 cc / min reactor to produce Zn
S: Cl was obtained. This thin film shows n-type, resistivity δ = 1 to 5Ω · cm, electron concentration 5 to 10 × 10 ¹⁷ cm
^-3, mobility μ = 50 to 100 cm ² / V · sec.

Similar to the doping of Cl, the doping of Br and I is performed by adding 1 to 2% HB diluted with a carrier gas.
r, HI gas was supplied into the reaction furnace. For Cl doping, instead of HCl, C
Similar doping characteristics were exhibited by using l ₂ .

In the case of doping using a liquid HBr, HI, Br ₂ , and Cl ₂ sealed cylinder, 100% gas supplied from the cylinder is previously supplied with a carrier gas whose flow rate is controlled by a mass flow controller. After diluting to 1-2%, the dopant gas cylinder 1
It may be supplied through the 0 pipe. The electrical characteristics of ZnS: X (X = Cl, Br, I) manufactured by the above method showed the same characteristics as ZnS: Cl manufactured using 1% HCl.

In the case of doping using solid I ₂ , I ₂ was crushed into fine powder, sealed in a bubbler 15, and I ₂ generated by sublimation was supplied into the reactor by a carrier gas. At a bubbler temperature of 30 ° C. and a carrier gas flow rate of 100 ml / min, ZnS: I having the same electrical characteristics as the above-mentioned ZnS: Cl was produced. However, the path from the bubbler 15 to the dilution line 18 was heated to 30 ° C. or higher to prevent the condensation of I ₂ .

In the case of doping using an organic substance containing a halogen element, a liquid substance was sealed in a bubbler 15 at room temperature, and then a carrier gas was bubbled at an appropriate temperature to be vaporized and supplied into a reaction furnace.

Dichlorobutane, dibromopropane and methylene iodide were respectively subjected to bubbling temperatures of -20 ° C and -5 ° C.
Zn produced using 1% HCl when bubbling at about 10 to 20 cc / min at 8 ° C. and 8 ° C.
ZnS: X having the same electrical characteristics as S: Cl was produced. No carbon peak was detected in the Auger spectrum of the grown film. In addition to the above-mentioned organic compounds, trichloroethane, trichloropropane, chlorobenzene, bromochloroethane, dibromoethane, ethyl iodide, propyl iodide, etc. If they were the same, they showed similar doping characteristics.

Regarding the ZnS: X produced as described above, regardless of the type of the substrate used for growth, when the film thickness is about 1 μm, the peak of the diffraction X-ray (400) by CuKα ray is Kα
1. Clear separation of the two peaks due to Kα2 was observed, and the half angle of the rocking curve was 0.15 to 0.2.
It was about 5 °. The electron diffraction image showed a clear spot pattern. On the other hand, an electron diffraction image of ZnS: X grown on a single crystal substrate by conventional evaporation or sputtering showed a pattern in which a ring indicating the presence of polycrystal and a spot corresponding to the single crystal coexisted. The crystallinity of ZnS: X produced by MOCVD is Zn
S: It turns out that it is very good compared with X.

ZnS: X (X
= Cl, Br, I) exhibited blue photoluminescence with a peak around 450-480 nm. As a typical photoluminescence spectrum, FIG.
Excitation wavelength of a ZnS: Cl thin film having a thickness of about 4000 Å prepared with 4-dichlorobutane as a dopant, 318 nm
Shows the spectrum at Z produced by conventional method
When the photoluminescence intensity was compared under the same conditions as nS: X, the intensity of the sample produced by the present invention was several times higher. The increase in photoluminescence intensity is
It is thought to be due to the improvement in the crystallinity of ZnS: X.

(Example 2) Zn shown in (Example 1)
ZnS on GaAs substrate similar to S: X growth
e: X growth is possible. The zinc source used was an adduct obtained by mixing dimethyl zinc and dimethyl selenium in equimolar amounts. This adduct is 46 mmTorr at 0 ° C.
It has a vapor pressure of about r. The growth conditions are shown below.

Bubbling amount of zinc source at −20 ° C. 25 ml / min, supply amount of 2% H ₂ Se diluted with He 100 ml / min, total gas flow rate including carrier gas 4.5 liter / min, growth temperature 300 ° C. ~ 5
00 ° C.

Under the above conditions, a growth temperature of 300 to
At 400 ° C., the growth rate was 0.7 to 0.9 μm / hr. At 400 to 500 ° C., it tended to decrease as the growth temperature increased. The introduction of the halogen element is based on the Z
It was carried out by supplying a chemical species containing a halogen element into the reaction furnace during nSe growth. The supply method is ZnS: X
The same as in the case of. Introduction of halogen element is IMA
(Ion microanalyzer).

(Example 3) Z shown in (Examples 1 and 2)
ZnS _1-x is grown similarly to the growth of nS: X and ZnSe: X.
The growth of Se _x : X is possible on a GaAs substrate. As a zinc source, dimethyl zinc or diethyl zinc,
An adduct obtained by equimolar mixing of diethyl sulfur or dimethyl zinc and dimethyl selenium was used. Further, H ₂ S and H ₂ Se are mixed and supplied at an appropriate ratio as a group VI source. ZnS _1-x Se _x solid phase composition in accordance with the mixing ratio of group VI source is obtained. The total amount of zinc source and two group VI sources, the same case, the growth rate of comparable ZnS _1-x Se _x is obtained (Example 1 and 2).
The same was true for the doping characteristics of the halogen element.

(Embodiment 4) In (Embodiments 1 to 3), epitaxial growth was performed on a single-crystal substrate. However, an amorphous substrate, for example, glass, quartz, or The formed Ta ₂ O ₅ , SiO ₂ , Al ₂ O ₃ ,
It can be laminated on a thin film such as ITO.

After the above substrate was washed, (Examples 1 to 5)
Growth of ZnS: X or the like was performed according to the process of 3).
The resulting thin film is a polycrystalline having as (111) orientation shows the diffraction X-ray pattern in Figure 3, the resistivity is 10 ⁸ ~
It was 10 ¹⁰ Ω · cm.

The photoluminescence spectrum had the same spectrum pattern except that the spectrum intensity was smaller than that of the single crystal film.

In exactly the same manner as in the above embodiment, ZnS: X on ZnS, ZnSe: X on ZnSe, ZnTe: X on ZnTe, ZnSe _1-x Te _x : X (0
<X <1) It is also possible to grow X = Cl, Br, I. Further, it is possible to dope a II-VI group compound semiconductor other than the above-mentioned compound semiconductor and a mixed crystal thereof with a halogen element.

[0038]

As described above, according to the present invention, when a II-VI group compound semiconductor thin film is formed by using the MOCVD method capable of forming a high quality thin film having excellent crystallinity, a chemical element containing a halogen element is used. By introducing the seed into the thin film forming atmosphere, halogen element doping can be performed with better controllability than the conventional vapor deposition, sputtering method and thermal diffusion method, and the crystallinity and photoluminescence characteristics are superior to the conventional method. It became possible to fabricate thin films. The thin film of ZnS: X (X: halogen element) produced according to the present invention can be applied as it is as a fluorescent material for a low-speed electron tube or a CRT. Further, by introducing Cu, Ag, or the like, it can be used as a light emitting layer of an electroluminescent panel. In addition, a blue light emitting diode can be manufactured by sequentially stacking an insulating film and an electrode layer to form a MIS structure in the single crystal thin film. It is convinced that the present invention makes a great contribution to the production of light emitting layers of various display devices and light emitting devices.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a MOCVD apparatus according to the present invention.

FIG. 2 is a diagram showing a typical photoluminescence spectrum of a thin film manufactured according to the present invention. (Spectrum of ZnS: Cl film measured at room temperature)

FIG. 3 Zn prepared on quartz glass according to the present invention
The figure which showed the diffraction X-ray pattern of S: Cl polycrystalline thin film.

[Explanation of symbols]

1. 1. Reaction tube made of transparent quartz Graphite susceptor with SiC coating 2. Substrate 4. Thermocouple 5. Heating furnace consisting of resistance heating, high frequency, infrared, etc. 6,7. Valve 8. Waste gas treatment system 9. Exhaust system 10. 10. Cylinder containing doping gas 11. A cylinder containing a Group VI hydride such as hydrogen sulfide Cylinder containing carrier gas 13. Purification device 14. 14. Bubbler containing Zn source 15. bubbler with dopant Mass flow controller 17. Valve 18. Dilution gas line 19. Three-way valve 20. Reaction tube introduction line 21. Bypass line

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[Procedure amendment]

[Submission date] November 29, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

1. An alkyl compound containing a group II element and a group VI element
An adduct consisting of an alkyl compound containing
A method for producing a group II-VI compound semiconductor thin film by a vapor phase thermal decomposition method of an organic metal, comprising introducing a chemical species containing a halogen element into the atmosphere for forming the group II-VI compound semiconductor thin film. -A method for producing a group VI compound semiconductor thin film.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

[0009]

Means for Solving the Problems The present invention is based on II-
Group VI compound semiconductor thin films are manufactured by
Consisting of a metal compound and an alkyl compound containing a group VI element.
Based on vapor phase pyrolysis of organometallics using additive as group II raw material
A method for producing a II-VI compound semiconductor thin film, comprising a halogen source
The chemical species containing element is added to the atmosphere for forming the II-VI group compound semiconductor thin film.
It is characterized by being introduced into the atmosphere. In addition, the halogen
Chemical species containing an element are X ₂ , HX (X = Cl, Br,
I) or an organic compound containing a halogen element
To collect. Also, the growth of the II-VI compound semiconductor thin film
The temperature is 300 ° C to 500 ° C.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

Carrier gas (He): total flow rate 4.5 liters / min Zinc source: 0 ° C bubbling amount of adduct by equimolar mixing of diethyl zinc-diethyl sulfur = 100 ml / min dimethyl zinc-diethyl sulfur equimolar mixture Bubbling amount of adduct by -20 ° C. = 15 ml / min He or H ₂ base 2% H ₂ S supply amount = 100 ml /
min Growth temperature 300 ° C. to 500 ° C. (The adduct in the present invention includes not only an adduct obtained by equimolar mixing of dialkylzinc and dialkylsulfur or dialkylselenium, but also a mixture obtained by equimolar mixing. Further, in the mixture, a part of the mixture forms an adduct and the other coexists in a dissociated state.) Under the above conditions, regardless of the growth temperature and the type of the growth substrate,
The growth rate is 0.8 to 1. It was almost constant at 0 μm / hr. The growth rate was the same even when the halogen element was doped.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

[0038]

As described above, according to the present invention, when a II-VI group compound semiconductor thin film is formed by using the MOCVD method capable of forming a good quality thin film having excellent crystallinity, a group II raw material is used.
Of an alkyl compound containing a group II element and an alkyl compound containing a group VI element
Using an adduct consisting of a alkyl compound and introducing a chemical species containing a halogen element into the atmosphere for forming the thin film,
As compared with the conventional vapor deposition, sputtering method and thermal diffusion method, the halogen element can be doped with better controllability, and it is possible to fabricate a thin film superior in crystallinity and photoluminescence characteristics to the conventional method. The thin film of ZnS: X (X: halogen element) produced according to the present invention can be applied as it is as a fluorescent material for a low-speed electron tube or a CRT. Further, by introducing Cu, Ag, or the like, it can be used as a light emitting layer of an electroluminescent panel. In addition, a blue light emitting diode can be manufactured by sequentially stacking an insulating film and an electrode layer to form a MIS structure in the single crystal thin film. It is convinced that the present invention makes a great contribution to the production of light emitting layers of various display devices and light emitting devices.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norihisa Okamoto 3-3-5 Yamato, Suwa City, Nagano Stock Company Suwa Seikosha

Claims (2)

[Claims] 1. A method for producing a II-VI group compound semiconductor thin film by vapor phase pyrolysis of an organic metal, wherein a chemical species containing a halogen element is introduced into the atmosphere for forming the II-VI group compound semiconductor thin film. II-VI group compound semiconductor thin film manufacturing method. 2. The chemical species containing the halogen element is X ₂ ,
The method for producing a II-VI group compound semiconductor thin film according to claim 1, which is an organic compound containing HX (X = Cl, Br, I) or a halogen element.