JPS6293989A - Hall element - Google Patents

Abstract

PURPOSE:To increase mobility in the conductive layer of a Hall element and make the thickness of the Hall element thinner by a method wherein a hetero junction is composed on a compound semiconductor substrate and a two-dimensional electron gas layer formed in the hetero junction boundary is utilized as the conductive layer. CONSTITUTION:A nondoped GaAs epitaxial layer 2 is formed on a GaAs substrate 1 and a silicon doped GaAlAs layer 3 is formed on the layer 2. Further, a nondoped GaAlAs layer 4 is formed between the layers 2 and 3 by utilizing a hetero junction boundary. A two-dimensional electron gas layer 5 is formed in the hetero junction boundary as a conductive layer by a molecular beam epitaxy method or the like. With this constitution, large mobility in the gas layer 5 of the Hall element can be obtained and the thickness of the Hall element can be reduced.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a Hall element, particularly a gallium-arsenide (Ga
A s ) It relates to a technique that is effective when applied to a Hall element using a semiconductor.

[Background technology]

The Hall element passes a current through the substance. It is an element that utilizes the so-called Hall effect, in which when a magnetic field is applied in the direction perpendicular to the current, a potential difference is generated in the direction perpendicular to both the current and the L fi field. The strength of the magnetic field is extracted as electricity (No. 3).

The Hall element based on this principle is Ga71.
s or indium-antimony (InSb). On the other hand, in order to make the Hall element high-temperature, carrier 4 is required as its material.
It is required to have a low temperature, high mobility, a small thickness including the conductive layer, and a large band gap so that it can be used even at high temperatures.

Incidentally, although InSb has high mobility, it has a small band gap, so there is a problem that it is difficult to use at high temperatures.

On the other hand, although GaAs has a large band gap, its mobility is lower than that of InSb, and although its thickness including the conductive layer can be made considerably thinner by ion implantation into semi-insulating GaAs, The inventors have discovered that there are limits to miniaturization and miniaturization of elements.

The Hall element and Hall IC are explained in "Comprehensive Electronic Components Handbook J," published by Dempa Shimbunsha, May 20, 1980, pages 564 to 569.

[Purpose of the invention]

An object of the present invention is to provide a technique that can increase the mobility of a conductive layer of a Hall element.

Another object of the present invention is to provide a technique that can reduce the thickness of a Hall element.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, by using the two-dimensional electron gas formed at the heterojunction interface on the compound semiconductor substrate as a conductive layer, impurity scattering can be eliminated and mobility can be increased.
Also, since it is a heterojunction structure,? It is possible to reduce the thickness of the pentaconductor layer and thus the Hall element.

[Example] FIG. 1 is a sectional view of a Hall element that is an example of the present invention.

The Hall element of this embodiment has a structure using C+aAs, and is formed by forming a non-doped GaAs epitaxial layer 2 on an S, [, type GaAs substrate l.

A silicon-doped GaAlAs layer 3 is formed on the GaAs layer 2, and both layers 2.
3 has a non-doped Ga
A s A l 54 is formed.

The heterojunction structure of this embodiment can be formed by, for example, MBE (molecular beam epitaxy) or MO/CVD.

A two-dimensional electron gas layer 5 is formed as a conductive layer at this heterojunction interface. Two-dimensional electron gas has no impurity scattering even if it smells at room temperature, so extremely high mobility can be obtained, and even higher mobility can be obtained at low temperatures. Of course, G
Being an aAs material, it can be advantageously used even at high temperatures.

Furthermore, the thickness of the conductive layer in the heterojunction structure is within 100 nm from the heterojunction interface, which can be much thinner than that achieved by, for example, ion implantation.

〔effect〕

(1) By making the two-dimensional electron gas layer formed at the heterojunction interface of the beterojunction groove formed on the compound semiconductor substrate into a four-electrode layer, holes with high mobility inherent to the two-dimensional electron gas element can be obtained.

(2+) According to the above (1), the thickness of the conductive layer and, by extension, the thickness of the Hall element can be made extremely thin due to the heterojunction structure.

(3) By using the above fll and f2+, it is possible to realize a Hall element that is far superior in terms of mobility and thickness compared to, for example, a Hall element obtained by ion implantation.

(4), above +11. +21, a highly sensitive Hall element can be obtained.

(By using a Hall element using a 51,0aAs semiconductor substrate, it is possible to effectively exhibit the effects of f1) to (4) above, and also realize a comprehensively excellent Hall element that is advantageous for use at high temperatures. can.

(6) Since conventional GaAs Hall elements use a protective film such as SiOt, there is a problem that the stress distribution between the substrate and the protective groin changes after the heat treatment process, increasing the unbalanced voltage. In the structure of the invention, since the GaAs material layer can be used as it is as a protective film, there is a possibility that a Hall element with less stress change with the substrate and a lower unbalanced voltage can be obtained.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the method for forming the heterojunction may be other than that described above.6 [Field of Application] The above description will mainly focus on the invention made by the present inventor, which is the field of application which is the background of the invention, GaAs'+ - Although the case where it is applied to a Hall element using a conductive substrate has been described, it is not limited thereto.
It can be widely applied to Hall elements using other compound semiconductor substrates such as Sb.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a Hall element that is an embodiment of the present invention.

1...GaAs group) anti, 2...non-doped QaA
s epitaxial layer, 3... silicon-doped GaA
pAs layer, 4...non-doped GaAsAl! [,5
...Two-dimensional electron gas layer.

Figure 1

Claims (1)

[Scope of Claims] 1. A Hall element characterized in that a two-dimensional electron gas layer formed at a heterojunction interface of a heterojunction structure formed on a compound semiconductor substrate is used as a conductive layer. 2. A two-dimensional electron gas layer is formed at a heterojunction interface between a silicon-doped gallium-aluminum-arsenide layer and a non-doped gallium-arsenide layer on a gallium-arsenide semiconductor substrate. The Hall element according to range 1.