JP2650635B2 - Method for producing II-VI compound semiconductor thin film - Google Patents

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, which is used for T, an electroluminescence panel, and a light emitting diode. More specifically, the present invention relates to a halogen element doping method for forming a II-VI compound semiconductor thin film by MOCVD.

[0002]

2. Description of the Related Art Conventionally containing a halogen element
The manufacturing method of the II-VI compound semiconductor thin film includes vacuum evaporation, electron beam evaporation, sputtering and the like. 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.

[0003] Other IEICE Technical Report 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.

[0005] 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.

[0006] 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.

Accordingly, the present invention is intended to solve such a problem. It is an object of the present invention to prepare a thin film having excellent crystallinity and orientation and to provide an MO having excellent control of doping.
An object of the present invention is to prepare a II-VI group compound semiconductor thin film containing a halogen element by using a CVD method.

[0009]

Means for Solving the Problems The present invention relates to the invention II-
The manufacturing method of Group VI compound semiconductor thin films is
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
In the atmosphere for forming the II-VI compound semiconductor thin film,
It is characterized by being introduced into the atmosphere. In addition, the halogen
When the chemical species containing the element is X ₂ , HX (X = Cl, Br,
I) or an organic compound containing a halogen element.
Sign. In addition, the growth of the II-VI compound semiconductor thin film
It is characterized in that the temperature is from 300C to 500C.

[0010]

FIG. 1 shows an MOCV used in the present invention.
1 shows a schematic view of a D apparatus. 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. Thermocouple 4 inside susceptor 2
The tip of the substrate is embedded to monitor the substrate temperature. A heating furnace 5 made of resistance heating, high frequency, infrared, 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 purification 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 dopants supplied from the cylinders 10 and 11 and the bubblers 14 and 15 are diluted by a carrier gas flowing through 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.
The substrate is heated to 600 ° C. and 900 ° C. to 1000 ° C. for a Si substrate. The oxide film remaining on the substrate surface can be removed by this thermal etching. After performing the thermal etching for 5 to 10 minutes, the substrate temperature is set to the growth temperature.

2. H ₂ S is supplied to the reactor 1 from the crystal growth cylinder 11. 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 each 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): 4.5 l / min total flow rate Zinc source: 0 ° C. bubbling amount of adduct by equimolar mixing of diethyl zinc-diethyl sulfur = 100 ml / min dimethyl zinc-diethyl sulfur equimolar -20 ° C bubbling amount of adduct by mixing = 15 ml / min He or H ₂ base 2% H ₂ S supply amount = 100 ml / min Growth temperature 300 ° C. to 500 ° C. (Adduct in the present invention means dialkyl zinc and And adducts obtained by equimolar mixing of dialkylsulfur or dialkylselenium, as well as mixtures obtained by equimolar mixing, in which some adducts are formed and others coexist in a dissociated state. Under the above conditions, the growth rate is 0.8 to 1 irrespective of the growth temperature and the type of the growth substrate. It was almost constant at 0 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, or 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 cooling the substrate, H ₂ S is switched to the bypass line 21 by operating a three-way valve, and then the supply of H ₂ S is interrupted and the inside of the reactor is evacuated to remove the remaining 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, and other organic substances composed of carbon, hydrogen, and a halogen element, supply amount of the halogen element is small. 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.

The 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 ZnS: Cl thin film having a thickness of about 4000 ° manufactured using 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
It is thought to be due to the improvement in the crystallinity of ZnS: X.

(Example 2) Zn shown in (Example 1)
In the same manner as the growth of S: X, ZnS
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.

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

Under the above conditions, a growth temperature of 300 to
At 400 ° C., the growth rate was 0.7-0.9 μm / hr. At 400 to 500 ° C., there was a tendency to decrease as the growth temperature increased. The introduction of the halogen element is based on the Z
During the nSe growth, a chemical species containing a halogen element was supplied into the reaction furnace. The supply method is ZnS: X
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 spectrum of the photoluminescence spectrum was the same 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) X = Cl, Br, I can be grown. 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 compound semiconductor thin film is formed by using the MOCVD method capable of forming a high-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,
It is possible to dope a halogen element with better controllability as compared with the conventional vapor deposition, sputtering, and thermal diffusion methods, and it is possible to produce a thin film that is 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 an MIS structure. We believe that the present invention contributes greatly to the production of light emitting layers of various display elements and light emitting elements.

[Brief description of the drawings]

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

FIG. 2 shows 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 shows Zn produced 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 2. Graphite susceptor with SiC coating 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 12. Gas cylinder containing carrier gas Purifier 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

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Norihisa Okamoto 3-3-5 Yamato, Suwa City, Nagano Prefecture Inside Suwa Seikosha Co., Ltd. 61-161710 (JP, A)

Claims (3)

(57) [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. 2. The method according to claim 2, wherein the chemical species containing a halogen element is X ₂ ,
2. The compound according to claim 1, wherein the compound is an organic compound containing HX (X = Cl, Br, I) or a halogen element.
Of group III compound semiconductor thin film. 3. A growth temperature of the II-VI compound semiconductor thin film.
Is 300 ° C. to 500 ° C.
2. The method for producing a group II-VI compound semiconductor thin film according to item 1.