JPH04298019A - Quantum well structure and its manufacture - Google Patents

Abstract

PURPOSE:To provide a quantum well structure which can attain satisfactory quantum effect and can improve characteristics of light emitting device, an electron transit device, etc., whereto it is incorporated. CONSTITUTION:A layer-like semiconductor region 14 which remains after etching has a thickness of about a de Broglie wave length. A semiconductor layer 12 supports a part 14a of the semiconductor region in the space on a substrate. Therefore, surfaces up and down the part 14a of the semiconductor region supported in the space is provided with a vacuum barrier and good quantum effect can be acquired.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quantum well structure used in light emitting devices, electron transport devices, etc., and a method for manufacturing the same.

0002

2. Description of the Related Art Conventional quantum well structures have been constructed by laminating, for example, two types of semiconductors with different band gaps. In such a quantum well structure, a semiconductor layer having a thickness on the order of the de Broglie wavelength and a small bandgap is generally sandwiched between semiconductor layers having a large bandgap. For this reason, the quantum effect in such a quantum well structure has a characteristic that the larger the heterobarrier caused by the difference in the band gap, the larger the quantum effect becomes.

0003

[Problems to be Solved by the Invention] However, in the junction between semiconductors such as the quantum well structure described above, this hetero barrier is about 1 eV at most, so it may not be possible to achieve a sufficient quantum effect. Ta.

Therefore, the present invention provides a quantum well structure that can achieve a sufficient quantum effect, and that makes it possible to improve various characteristics of light emitting devices, electron transport devices, etc. incorporating the quantum well structure. The purpose is to provide a method for producing the same.

[0005]

[Means for Solving the Problems] In order to achieve the above object, a quantum well structure according to the present invention includes (a) a layered semiconductor region having a thickness of approximately the de Broglie wavelength; and (b) a semiconductor region. and support means for supporting a portion of the substrate in a hollow space above the substrate.

The method for manufacturing a quantum well structure according to the present invention also includes the steps of (a) growing a first semiconductor layer on a substrate; (c) etching predetermined portions of the first and second semiconductor layers to form a mesa-shaped region including the first and second semiconductor layers; (d) forming a mask having an opening in the stepped portion of the mesa-shaped region; and (e) performing material-selective etching on the opening of the mask to remove a predetermined portion of the first semiconductor layer. It is planned to have a process.

[0007]

According to the quantum well structure described above, the supporting means supports a part of the layered semiconductor region having a thickness of approximately the de Broglie wavelength in a hollow space above the substrate. Therefore, a vacuum barrier is formed on the surface of the semiconductor region supported in the air, and an effective quantum effect can be obtained.

Further, according to the method for manufacturing a quantum well structure described above, a second semiconductor layer supporting the second semiconductor layer is formed between the substrate and the second semiconductor layer having a thickness of approximately the de Broglie wavelength. 1
A semiconductor layer is provided in advance, and this first semiconductor layer is partially removed by etching. Therefore, the second semiconductor layer can be easily supported in the air, and a vacuum barrier that can effectively achieve the quantum effect can be formed on the surface of the second semiconductor layer with a thickness of approximately the de Broglie wavelength. .

[0009]

EXAMPLE FIG. 1 shows a method of manufacturing a quantum well structure according to an example.

First, an InP layer 12 is formed on an InP substrate 10.
and GaInAs layers 14 are alternately lattice-matched and epitaxially grown to form a laminated structure (FIG. 1(a)). The thickness of these layers 12 and 14 is approximately the de Broglie wavelength. Next, a suitable mask is formed on the laminated structure consisting of the layers 12 and 14 and etching is performed to form a mesa-shaped region 20 consisting of the layers 12 and 14 (FIG. 1(b)). Thereafter, a mask made of SiO2, SiNX, etc. is formed leaving an opening area across the center of the mesa-shaped region 20, and this opening area is etched using an etching solution containing hydrochloric acid as a main component. In this case, since the cross section of the layers 12 and 14 is formed within the opening region, the InP layer 12 is eroded from this cross section. Thereafter, the mask is removed to obtain a quantum well structure (FIG. 1(c)). In other words, the remaining InP layer 12
The upper and lower surfaces of the GaInAs layer 14 supported by the GaInAs layer 14 are exposed in the air. This GaInAs layer 14 becomes a quantum well layer.

FIG. 2 is a diagram showing the energy levels of the quantum well structure of FIG. 1.

The semiconductor region in which the GaInAs layer 14 remains has both side surfaces exposed to the air, so that vacuum barriers are formed on both sides. Therefore, electrons existing in the quantum level of the conduction band edge Ec of this semiconductor region are confined within an ideal energy barrier of about 5 eV, which corresponds to electron affinity. Furthermore, holes existing at the quantum level at the valence band edge Ev are also confined within the ideal barrier. As a result, it is possible to provide new characteristics to light emitting devices, electron transport devices, etc., such as reducing the threshold current of a semiconductor laser, or to improve these characteristics.

The present invention is not limited to the above embodiments. For example, the InP layer 12 is completely removed and the GaInAs layer 14 is completely removed.
The mask may remain for support. Furthermore, if an etching solution containing phosphoric acid as a main component is used instead of an etching solution containing hydrochloric acid as a main component, the GaInAs layer 14 instead of the InP layer 12 will be eroded. Therefore, G
The InP layer 12 supported by the aInAs layer 14 becomes a quantum well layer.

[0014]

According to the quantum well structure of the present invention, a vacuum barrier is formed on the surface of the semiconductor region supported in the air. Therefore, an effective quantum effect can be obtained within the hollowly supported semiconductor region. If this quantum well structure is applied to light emitting devices, electron transport devices, etc., new characteristics can be imparted to these devices, and these characteristics can be improved.

Further, according to the above method for manufacturing a quantum well structure, the first semiconductor layer is provided in advance between the substrate and the second semiconductor layer, and the first semiconductor layer is partially etched. It is being removed. Therefore, the second semiconductor layer having a thickness of approximately the de Broglie wavelength can be easily supported in the air, and a vacuum barrier that can effectively achieve the quantum effect is formed on the surface of the second semiconductor layer. can.

[Brief explanation of the drawing]

FIG. 1 shows steps of a method for manufacturing a quantum well structure according to an example.

FIG. 2 is an energy band diagram of the quantum well structure of the quantum well structure of FIG. 1(c).

[Explanation of symbols]

10...Substrate 14...Layered semiconductor region 12...Supporting means

Claims (2)

[Claims] 1. A quantum well structure comprising a layered semiconductor region having a thickness on the order of the de Broglie wavelength, and support means for supporting a portion of the semiconductor region in a hollow space above a substrate. 2. A step of growing a first semiconductor layer on a substrate, a step of growing a second semiconductor layer having a thickness of about de Broglie wavelength on the first semiconductor layer, and a step of growing a second semiconductor layer on the first semiconductor layer, 1
and etching a predetermined portion of the second semiconductor layer,
forming a mesa-shaped region including the first and second semiconductor layers; forming a mask having an opening in a stepped portion of the mesa-shaped region; and performing material-selective etching on the opening of the mask. , a step of removing a predetermined portion of the first semiconductor layer.