JPH04349194A - Production of zinc selenide - Google Patents

Abstract

PURPOSE:To produce a low-resistance p-type zinc selenide by irradiating a substrate with an electron beam while doping by a radical to move a group atom not accurately positioned into an accurate selenium site by the energy of the electron beam. CONSTITUTION:The surface of a substrate 3 is irradiated with the radical 9b contg. a group V element and an electron beam 12b, when zinc and selenium are simultaneously vapor-deposited by molecular beam epitaxy. Since the radical 9b is electrically neutral and high in reactivity, zinc selenide 4 being produced is not damaged, and a sufficient amt. of a group V atom 10 is doped. Meanwhile, the atom 10, which is placed in zinc selenide but not accurately positioned in the selenium site, is moved into the accurate selenium site by the energy of the electron beam 12b because the substrate is simultaneously irradiated with the electron beam 12b, and high-quality low-resistance p-type zinc selenide 4 is obtained.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for producing zinc selenide, which is a promising material for blue light emitting devices.
In particular, it relates to a method for producing p-type zinc selenide.

0002

2. Description of the Related Art Group II-VI compounds are semiconductors with a wide forbidden band width and are expected to be used as light-emitting devices ranging from green to ultraviolet. In particular, zinc selenide (ZnSe) has a forbidden band width of about 2.7 eV at room temperature and is therefore promising as a highly efficient light-emitting element in the blue region. However, high-quality, low-resistance p-type zinc selenide necessary for constructing high-efficiency light-emitting devices has not been obtained. Conventionally, in an attempt to obtain p-type zinc selenide, molecular beam epitaxy (MBE) was used to simultaneously deposit zinc (Zn) and selenium (Se).
There is a method of ionizing doping using a group element such as nitrogen as an impurity, and it has been confirmed that an acceptor level is formed in zinc selenide by this method.

0003

[Problems to be Solved by the Invention] However, when attempting to ionize and dope a sufficient amount of nitrogen to obtain a low-resistance p-type zinc selenide, there is a problem in that the film becomes polycrystalline due to ion damage. Ta.

The object of the present invention is to solve the above problems and provide a method for producing high quality, low resistance p-type zinc selenide.

[0005]

[Means for Solving the Problems] In order to achieve this object, the present invention irradiates the surface of a substrate with a selenium molecular beam and a zinc molecular beam in a vacuum, and also irradiates the surface of the substrate with radicals containing group V elements and an electron beam. zinc selenide is produced by irradiating the

[0006]

[Operation] In the present invention, doping with radicals containing a group V element is used instead of ionization doping of a group V element in the conventional method. Since radicals containing group V elements are electrically neutral, they do not damage zinc selenide, and since they are extremely reactive, they can be doped with a sufficient amount of group V atoms. However, group V atoms doped into zinc selenide act as p-type impurities only when they are precisely located on selenium sites, but they often shift from selenium sites and enter zinc selenide, resulting in low resistance p-type impurities. It does not become type zinc selenide. On the other hand, according to the method of the present invention,
By irradiating electron beams while doping with radicals, the energy of the electron beams can move group V atoms that are not located precisely and place them in the correct selenium sites, resulting in low-resistance p-type zinc selenide. Can be manufactured.

[0007]

[Example] Specific examples will be described in detail below. FIG. 1 shows a schematic diagram of a molecular beam epitaxy apparatus used in an embodiment of the present invention.

First, the substrate 3 whose surface has been cleaned is mounted on the substrate holder 5. Suitable substrate materials include single crystals of zinc selenide itself and single crystals of gallium arsenide (GaAs) having a lattice constant close to that of zinc selenide. In this case, gallium arsenide single crystal was used. Next, the vacuum chamber 1 is evacuated to an ultra-high vacuum of about 10 -9 Torr or less using the vacuum pump 2 . Thereafter, with the shutter 13 closed, the crucibles 7a and 8a are heated by the heaters 7b and 8b, and the shutters 7c and 8c are opened, and the zinc and selenium molecular beams 7d,
The intensity ratio of 8d is set to 1.

Next, the substrate 3 is heated to about 600° C. to further clean the surface. Thereafter, the substrate 3 is lowered to a temperature suitable for zinc selenide growth. In this case, the temperature is, for example, 325°C. Next, the flow control valve 11 is opened to allow the group V raw material 10, in this case, nitrogen (N2), for example, to flow into the radical generator 9a. In this case, for example, the pressure inside the vacuum chamber 1 is 1×10-6To
Nitrogen was flowed so that the temperature was about rr, and a high frequency discharge of, for example, 13.56 MHz was used as a radical generating means. Next, for example, high frequency power of 100 W is applied to generate nitrogen atoms or molecular radicals 9b in the radical generator 9a. The radicals 9b generated in the radical generator 9a are transferred from the radical generator 9a to the vacuum chamber 1 due to the pressure difference between the radical generator 9a and the vacuum chamber 1.
released within. Further, the electron beam 1 from the electron beam source 12a is
Generate 2b. In this case, for example, the acceleration voltage of the electron beam 12b was set to 5 kV, and the emission current was set to 10 μA. Next, open the shutter 13 and combine the molecular beams 7d and 8d with the radical 9.
b Furthermore, the surface of the substrate 3 is irradiated with the electron beam 12b.

The zinc selenide produced by the method described above was a single crystal of good quality. In addition, by adjusting the nitrogen flow rate and high frequency power, the carrier density can be increased from 1016 to 101.
9cm-3 of p-type zinc selenide could be produced.

In the above embodiment, nitrogen (N
) was selected and nitrogen was used as the group V raw material, but ammonia (
A similar effect can be obtained by using other gases such as NH3). Similarly, the same effect can be obtained by selecting phosphorus (P) or arsenic (As) as the V group element and using phosphine (PH3), arsine (AsH3), or the like.

Although high frequency discharge was used as the radical generating means in the above embodiment, other means such as generating radicals by photodecomposition of group V raw materials may also be used. The light source may be selected according to the absorption band of the raw material used.

[0013] Furthermore, the accelerating voltage of the electron beam is 1 kV or more.
A suitable value is kV or less, and an appropriate emission current is 1 μA or more and 500 μA or less. If the accelerating voltage and emission current are too small, group V atoms that are not located in selenium sites cannot be moved and placed in the correct selenium sites, and if they are too large, defects will occur in the produced zinc selenide.

[0014] Also, the substrate temperature during zinc selenide production is 2
The temperature is preferably 00°C or higher and 500°C or lower. At temperatures below 200°C, each atom is not stabilized in its correct lattice position, and at temperatures below 500°C,
This is because in the above case, the re-evaporation of atoms becomes excessive and vacancies of atoms are generated, so that a perfect crystal cannot be obtained in any case.

As explained above, according to this embodiment, when the surface of the substrate 3 is irradiated with the radicals 9b containing group V elements and the electron beam 12b during simultaneous vapor deposition of zinc and selenium using the molecular beam epitaxy method, the radicals are Since 9b is electrically neutral, it does not damage the zinc selenide 4 produced, and because it is highly reactive, a sufficient amount of group V atoms 10
can be doped. Furthermore, by simultaneously irradiating the electron beam 12b, group V atoms 10 that exist in zinc selenide but are not located in the correct selenium site can be moved by the energy of the electron beam 12b and placed in the correct selenium site. . As a result, high quality low resistance p
Type zinc selenide 4 can be obtained.

[0016]

As described above, the method of the present invention irradiates the substrate surface with selenium molecular beams and zinc molecular beams in vacuum, and irradiates the substrate surface with radicals containing group V elements and electron beams. , it is possible to efficiently and rationally produce high-quality, low-resistance p-type zinc selenide, which is very important in constructing a high-efficiency blue light-emitting device.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a molecular beam epitaxy apparatus used in one embodiment of the present invention.

[Explanation of symbols]

1 Vacuum chamber 2 Vacuum pump 3 Board 4 Zinc selenide 5　Substrate holder 6 Heater 7a Crucible 7b Heater 7c Shutter 7d Molecular beam of zinc 8a Crucible 8b Heater 8c Shutter 8d Molecular beam of selenium 9a Radical generator 9b Radical 10 Group V raw materials 11 Flow control valve 12a　Electron beam source 12b Electron beam 13 Shutter

Claims (1)

[Claims] 1. A method for producing p-type zinc selenide, comprising: irradiating a substrate surface with a selenium molecular beam and a zinc molecular beam in a vacuum; and irradiating a radical containing a Group V element and an electron beam onto the substrate surface. A method for producing zinc selenide, comprising irradiation.