JPH03169091A - Manufacture of quantum fine line - Google Patents

Abstract

PURPOSE:To narrow the width of a quantum fine line enough by stacking semiconductor layers of nondope and semiconductor layers doped in high concentration with impurities alternately on a semiconductor substrate, and forming quantum well layers at the cross sections of these semiconductor layers, and then diffusing impurities into the quantum well layers. CONSTITUTION:Undoped semiconductor layers 102 and semiconductor layers 103 doped with impurities in a high concentration are made alternately on a semiconductor substrate 101, and one part each or the whole parts of the semiconductor layers are exposed. And a quantum well layer 110 is laminated on this exposed part, and impurities diffuse from the semiconductor layers 103 doped with impurities, and they disorder the quantum well layer 110 partially, and form quantum fine lines 130 at the parts being not disordered. Hereby, quantum fine lines having narrow widths can be made easily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a quantum wire that allows narrowing of the quantum wire convergence.

[Conventional technology]

As methods for producing quantum wires, the methods shown in FIGS. 2(a) to 2(Q) are known so far. This method uses Ga
A multiple quantum well layer 110 consisting of a GaAs well layer with a thickness of about 1006 and a klGaAs (x=about 0.3) barrier layer with a similar thickness is formed on an As substrate 101 by MOCVD or MBE. Figure 2 (a)
). Next, a) SiN film 201 is formed on the multiple quantum well [1110] by thermal CVD. Appropriate thickness is about 500 mm. Next, the window 202 is opened using a normal photolithography method or an electron beam exposure method [FIG. 2(b)]
In order to form an O quantum wire, it is necessary to set the interval between windows to several hundred λ or less.

Next, impurities such as Zn are selectively diffused into the multiple quantum well layer 110 through the window 202 by a closed tube or open tube diffusion method. In the Zn diffusion region 120 where Zn is diffused, a disordering phenomenon occurs in which the composition of the well layer and the barrier layer becomes average. In the portions where Zn is not diffused, the composition at the time of crystal growth remains as is. If the width of this non-diffused region is several hundred λ or less, this region becomes a quantum forest 130 [Fig.
Q)E. In this manufacturing method, the thickness of the quantum wire 130 is determined by the spacing of the windows 202 for diffusion. However, normal photos! ! ! In the printing method, the interval between windows 202 is 1
The best I can do is stay below 0000 seconds. Even with electron beam exposure or interference exposure, it is difficult to obtain a window spacing of about 1000λ. In order to bring out the performance of the quantum wire 130, the quantum wire width (in other words, the distance between the diffusion windows) must be 10
It needs to be around 05. Therefore, with the conventional manufacturing method, the characteristics of the quantum thin film IL130 could not be fully exhibited.

[Problem to be solved by the invention]

As is clear from the above description, the conventional method for manufacturing quantum wires has an essential problem in that the width of the quantum wires cannot be made sufficiently narrow.

This invention was made to solve the above-mentioned problems, and aims to provide a method for manufacturing a quantum wire that can sufficiently narrow the width of the quantum wire.

[Means to solve the problem]

A method for manufacturing a quantum wire according to the present invention includes a step of alternately forming an undoped semiconductor layer and a semiconductor layer doped with a high concentration of impurities on a semiconductor substrate, and A process of exposing the entire quantum well layer, a process of stacking a quantum well layer on this exposed part, and a process of diffusing impurities from the impurity-doped semiconductor layer to partially disorder the quantum well layer and place quantum wires in the non-disordered parts. It consists of a step of forming.

[Effect]

In this invention, undoped semiconductor layers and semiconductor layers heavily doped with impurities are alternately laminated on a semiconductor substrate, a quantum well layer is formed in the cross section of these semiconductor layers, and the impurity is doped. Since the impurity is diffused into the quantum well layer, the semiconductor layer heavily doped with impurities acts as a diffusion source for selective diffusion, and is diffused into the quantum well layer to form a narrow quantum wire.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1(a) and 1(b).

In FIG. 1(a), 101 is a GaAs substrate, 102
103 is an undoped AjGaAg layer, 103 is a p''-GaAs layer heavily doped with impurities, and 104 is a Ga
It is an As layer.

Next, the operation will be explained.

First, as shown in FIG. 1(a), on a GaAs substrate 101 having the (100) plane as its main surface, an undoped AIGaAa layer 102 and a p layer doped with impurities to an ilrs degree are formed.
The +-GaAs layer 103 is grown by MBE method or the like. The number of pairs of two layers may be one, or there may be many pairs as necessary. The thickness of the undoped At'GaAs layer 102 corresponds to the conventional diffusion window 202.

Therefore, the thickness of this undoped At'GaAs layer 1o2 determines the desired width of the quantum wire. In order to fully obtain the effect of quantum wires, it is necessary to use non-doped AIGaA.
The appropriate thickness of the s-layer 102 is 100 to 500λ. If the thickness is around this level, MBE method or MOCV method can be used.
You can grow without any difficulties using method D. The thickness of the p''-GaAs layer 103 may be selected to be approximately the same as the thickness of the undoped AjGaAs layer 102.The impurity concentration of the p''-GaAs layer 103 is set to 5×101 so that this layer acts as a diffusion source.
Set it to about 婁cm-" to IXIO"am-'.

Zn is suitable as a dopant.

Next, this grown wafer is opened at the arms along the <100> direction to form a (110) plane 105 as shown in FIG. 1(b). This newly formed (1 1 0) plane 10
On top of 5, crystal growth is performed again to grow a multiple quantum well layer 110 in which quantum wires are to be formed. This wafer
For example, when heat treatment is performed at 850° C. for several hours under arsenic pressure, Zn undergoes so-called out-diffusion, and non-doped A4! Zn diffusion regions 120 are formed at intervals determined by the thickness of the GaAs layer 102. This Zn diffusion region 120 is disordered. The region surrounded by the Zn diffusion region 120 is not disordered and becomes a quantum wire 130 with a width of several hundreds. The width of the quantum wire 130 is determined by the thickness of the undoped A4'GaAs layer 102 in the quantum well layer structure serving as a diffusion source, and the quantum wire P.
Although the thickness of $1.30 is determined by the thickness of the multi-quantum well layer 110 to be formed, it is clear that according to the present invention, it is easy to obtain a width of several hundred six, which was difficult with conventional techniques. It is.

In the above description, the region to be doped with a high concentration is GaAsJij, but AjGaAs may be doped with a high concentration. Alternatively, the entire layer may be made of GakSM to form a heavily doped region and an undoped region.

One type of high concentration layer was made by Zn doping, but Si
and Zn may be doped alternately.

In this case, the resulting quantum wire is the so-called nipi
It can be a structure. Undoped AjGaAs layer 1
The thickness of 02 does not necessarily need to be constant, and may be changed periodically or randomly.

In addition, a second
Although the second crystal growth was performed, it does not necessarily have to be the (110) plane; for example, the same effect can be obtained by forming a second multiple quantum well structure on the plane formed by etching etc. It is obvious. In addition, quantum wire 130
The quantum well layer to be formed is not limited to multiple quantum well layers, but may be a single quantum well layer. For convenience of explanation, GaAs is used as an example here, but other semiconductors,
It is clear that the present invention can also be applied to IpP, InGaAs1S i, Ge, etc., for example.

〔Effect of the invention〕

As explained above, the present invention includes a process of alternately forming undoped semiconductor layers and semiconductor layers heavily doped with impurities on a semiconductor substrate, and a process of forming a part or the entire cross section of each semiconductor layer. A step of exposing the quantum well layer, a step of stacking a quantum well layer on this exposed portion, and a step of diffusing impurities from the impurity-doped semiconductor layer to partially disorder the quantum well layer and form quantum wires in the non-disordered portions. Since the process consists of the following steps, it is possible to easily form a quantum wire having a width of several hundred or less.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating a method for manufacturing a quantum wire according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing a conventional method for manufacturing a quantum wire. In the figure, 101 is a GaAs substrate, and 102 is an AjGa substrate.
As layer, 103 is p''-GaAs layer, 104 is GaA
110 is a multi-quantum well layer, 120 is a Zn diffusion region, and 130 is a quantum wire. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] A step of alternately forming an undoped semiconductor layer and a semiconductor layer doped with a high impurity concentration on a semiconductor substrate, a step of exposing a part or the entire cross section of each semiconductor layer, and the exposed portion and a step of diffusing impurities from the impurity-doped semiconductor layer to partially disorder the quantum well layer and form quantum wires in the non-disordered portions. Characteristic method for producing quantum wires.