JPS63120413A - Molecular beam cell - Google Patents

Abstract

PURPOSE:To realize a uniform strength of molecular beams on substrate crystals and to enable an introduced organic metal compound material to reach the substrate crystals effectively, by providing a heater wire between inner and outer insulating cylinders, arranging disks having holes formed at positions deviated from each other and providing a thermal shield plate on the outside. CONSTITUTION:A molecular beam cell used for a molecular beam growth in which organic metal compound gas is used as a depositing material is constructed by spacing two or more disks 16, 17 in a first insulating cylinder 12, the disks having holes opened at position deviated from each other; providing a heater wire 14 on the periphery of the first insulating cylinder 13; providing a second insulating cylinder 13 outside of the heater wire 14; and providing a thermal shield plate 15 outside of the second insulating cylinder 13. For example, thatalum heater wire 14 is provided between an inner quartz cylinder 12 having a quartz introduction tube 11 and an outer quartz cylinder 13, and a tantalum plate as the thermal shield plate 15 is rolled around the outer quartz cylinder 13. Tantalum disks 16, 17 having holes formed at positions deviated from each other are arranged within the inner quartz cylinder 12 with tantalum rings 18 interposed therebetween.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a molecular beam cell used in a molecular beam growth apparatus that grows crystals by irradiating the surface of a growth substrate with a gas containing an organometallic compound gas.

[Conventional technology]

Molecular beam epitaxy (hereinafter abbreviated as MHD method) and metal organic vapor phase epitaxy method (abbreviated as MOVPI) are thin film semiconductor epitaxial crystal growth techniques with excellent film thickness controllability.
It is used in the production of optical and electronic devices. However, these methods have various drawbacks, and in order to solve these drawbacks, in recent years, the molecular beam growth method (hereinafter referred to as MOMB) using organometallic compound gas as a growth material has been developed.
(abbreviated as E method) was proposed (Asahi, Oishi, Nagai, J-J-7ri 3g) and developed (for example, Y,
Kawaguchi+1-1- Asahi + Ho
Nagai + Japan J-Appl-Phys
-23 (/Rizag) L737).

In the MOMBII method, the growth raw material is supplied in the form of molecular beams, so in order to obtain crystals with uniform composition and thickness within the epitaxial crystal plane, the molecular beam intensity must be uniform on the substrate crystal plane. It is necessary to supply it as follows. As a conventional molecular beam cell for this purpose, there is one shown in FIG. Third
In the figure, / is a capillary tube, ! is the beam dispersion chamber,
3 is a gas dispersion plate, and G is a molecular beam exit port.

In the molecular beam cell shown in Fig. 3, the original T1 gas introduced into the molecular beam cell cannot travel straight to the molecular beam exit port due to the gas dispersion plate, and is subjected to multiple scattering to ensure uniform molecular beam intensity. conversion is carried out. However, in order to obtain high-purity Evitagishel crystals, - Generally, a shroud filled with liquid nitrogen is provided around the molecular beam cell. For this reason, the molecular beam cell is cooled and the organometallic compound, which is the raw material gas, is adsorbed inside the molecular beam cell, making it difficult to control the molecular beam intensity, and at the same time, the organometallic compound raw material cannot be used effectively. Furthermore, in the conventional cell shown in Fig. 3, the molecular beam intensity was not sufficiently uniform, and the distance between the cell and the substrate was
The object of the present invention is to solve these drawbacks and to provide a low-cost molecular beam cell for organometallic compounds. There is a particular thing.

[Structure of the invention]

The present invention has a heater wire between two concentric insulating cylinders, and inside the heater wire, there is a disk with a hole in the center and a disk with a hole at the off-center position W4. Two or more sheets are arranged alternately at intervals of 1 inch (6), and heat is applied to the outside of the heavy insulating cylinder.
! :The main feature is that it has a B mask. The conventional technology differs from the conventional technology in that it has a structure that suppresses the adsorption of organometallic compounds by arranging heater wires, and is simple in that it has a structure in which disks with different hole positions (16) are stacked alternately at intervals. It differs in that it has a structure that reliably evens out the molecular beam intensity.

〔Example〕

FIG. 1 Ul2 is a diagram illustrating the present invention in detail,
/ 21tJ quartz introduction tube for metal compound gas
, an inner quartz cylinder, /3 an outer quartz cylinder, /,2. /3 has a concentric axis relationship.

/4tIJ, tantalum heater wire, /,2. /
3 realizes electrical insulation. /j is a tantalum heat shield plate, which is constructed by wrapping a tantalum plate around an external quartz cylinder. /B is a tantalum disk with a hole in the center as shown in Figure 2 (a), /7 is a tantalum disk with a hole at 16 degrees off center as shown in Figure 2 (b) , /r is a tantalum ring shown in FIG.

In this molecular beam cell, the organic metal compound is introduced by passing a current through the heater wire and heating it to an appropriate temperature (!0~/00'C) at which the organometallic compound will not be thermally decomposed and will not be adsorbed inside the cell. The organometallic compound effectively reaches the substrate crystal without being adsorbed inside the cell. For this reason,
By controlling the amount introduced into the cell, the molecular beam intensity can be controlled with high precision.

In addition, since the disks with different hole positions are stacked alternately, organometallic compounds cannot be predicted if they move straight inside the cell.
As a result of multiple scattering, an organometallic compound molecular beam with spatially uniform intensity is obtained. By appropriately selecting the number of tantalum disks at intervals of two, it is possible to easily generate a molecular beam of uniform intensity on a large area of the substrate crystal surface. Furthermore, since the heater wire is sandwiched between double quartz cylinders, the problem of adsorption can be easily and inexpensively suppressed. By using trimethylindium and triethylgallium, which are organometallic compounds, as raw materials for device beams, and arsine as raw materials for V device, an In<)aAs compound semiconductor epitaxial crystal was formed on an InP substrate as a cell and substrate. The distance between /
It was grown in a 2-inch diameter substrate with a narrow half-width of 27 seconds as a double-crystal X-ray diffraction pattern.
The composition deviation of the InGaAs layer at 1- is highly uniform at 10:, #%, and the electron mobility at 77 is '10, #%.
000*/V・S and high quality formal crystals were obtained. Further, when growing a crystal of the same thickness, the amount of consumption of the non-contact metal compound was less than 20 minutes when the conventional cell shown in FIG. 8 was used. In the conventional cell, most of the organometallic compounds were adsorbed to the cell and did not participate in growth, and only a small amount participated in growth, whereas in the cell of this example, d2 ,
This is because the organometallic compound is supplied onto the substrate without being adsorbed to the cell.

〔Effect of the invention〕

As explained above, according to the present invention, uniform molecular beam intensity can be achieved on the substrate crystal, and the introduced organometallic compound raw material can effectively reach the substrate crystal, so that the crystal composition and crystal thickness can be reduced. It has the advantage of being able to grow uniform, high-quality epitaxial crystals. Furthermore, since the molecular beam cell according to the present invention has a simple structure, it has the advantage that it can be used as a simple and inexpensive molecular beam cell.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a molecular beam cell of the present invention, FIG. 2 is a diagram showing some of the constituent parts of the molecular beam cell of the present invention, and FIG. 3 is a sectional view of a conventional molecular beam cell. /... Capillary tube, 2... Beam dispersion chamber, 3...
...Gas distribution plate, G...Molecular beam exit port, //...Quartz introduction tube, /2. /3...Quartz cylinder, /ri°...
Tantalum heater wire, /1. ...Tantalum disk in Fig. 3(a), /7...Tantalum disk in Fig. 2(b), /
I... Tantalum ring in Figure 2 (C), /J-, /
9.20...Tantalum heat treated shield plate.

Claims (1)

[Claims] In a molecular beam cell for molecular beam growth using organometallic compound gas as a growth raw material, two or more disks with holes at mutually shifted positions are spaced inside a first insulating cylinder. A heater wire is provided outside the first insulating tube, a second insulating tube is provided outside the heater wire, and a heat shielding plate is provided outside the second insulating tube. A molecular beam cell characterized by: