JPH0923025A - Manufacture of semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor element manufacturing method by which the characteristics of a semiconductor element having a quantum dot structure can be improved. SOLUTION: At the time of forming semiconductor microcrystals in a quantum dot structure, semiconductor crystals for forming the microcrystals and semiconductor crystals for forming an energy barrier are selected by using a organometallic chemical vapor growth method so that a lattice constant difference of 1% or more in a bulk state can be obtained between the semiconductor crystals and the V/III ratio which is one of the growing conditions of the microcrystals is adjusted to 100-200.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device having good sensitivity for receiving and emitting light.

[0002]

2. Description of the Related Art Conventionally manufactured semiconductor devices using semiconductor quantum dots have not been provided with sufficient characteristics such as small emission intensity and light receiving sensitivity, wide emission half width and light receiving band.

[0003]

This is because the density of the semiconductor crystallites in the quantum dot structure is low and the size uniformity is poor. The present invention, in order to solve the above problems, a method of manufacturing a semiconductor quantum dot structure for improving the density of the crystallites and the uniformity of the size thereof in the semiconductor quantum dot structure and obtaining sufficient device characteristics. Is provided.

[0004]

In order to solve the above-mentioned problems, a manufacturing method provided by the present invention is a semiconductor microcrystal made of a semiconductor having a cross-sectional size of about the de Broglie wavelength of an electron, and a potential energy. Is higher than the potential energy of this semiconductor microcrystal and functions as an energy barrier.
In manufacturing a semiconductor device having a three-dimensional quantum well (quantum dot), metal organic chemical vapor deposition (MO) is used for crystal growth.
The CVD method) is used to form a microcrystal so that the lattice constant of the semiconductor crystal forming the microcrystal in the bulk state and the base during the growth of the microcrystal and the covering after the formation of the microcrystal are covered. By using three-dimensional growth in a lattice-mismatched system by using a material having a lattice constant that differs by 1% or more in the bulk state of a semiconductor crystal that is grown to form an energy barrier, the crystal material As a condition, a ratio (V /
A method of manufacturing a semiconductor device, characterized in that fine crystals are grown in a value of (III ratio) in the range of 100 to 200.

The plane orientation of the substrate is (100).
Therefore, this effect becomes remarkable when the one turned off by 2 ° to 8 ° in the <110> direction is used. In the case where a quantum dot structure is manufactured by using the above method, Al _x Ga _1-x As (0 ≦ x ≦ 1) is used as a semiconductor crystal for forming microcrystals.
As GaA as a semiconductor crystal forming an energy barrier
It is preferable to use s _1-y P _y (0.25 ≦ y ≦ 1).

[0006]

By using the above-described manufacturing method, it is possible to obtain a larger density of crystallites and a greater uniformity of size in the quantum dot structure than in the conventional case. Further, in a semiconductor device using this, it is possible to improve the characteristics such as higher emission intensity / light receiving sensitivity, narrow emission half width / light receiving band, and the like, as compared with the conventional ones.

[0007]

Next, an embodiment of the present invention will be described with reference to the drawings. First, the influence of the V / III ratio, which is one of the growth conditions during the formation of semiconductor crystallites, was investigated. The sample was manufactured by the following method. The surface of the substrate is (100)
A plurality of n-type GaP semiconductor substrates each having a plane orientation with an off angle from the to <110> direction of 0 ° to 10 ° were used. Epitaxial growth is based on metal organic chemical vapor deposition (MOC).
VD method). First, the substrate, which has been subjected to cleaning with an organic solvent and surface etching, is set in a MOCVD apparatus. This is heated to a predetermined temperature, and a GaP buffer layer, GaAs _0.50 P _{0.50 is formed} on this substrate.
The base layer was sequentially formed by crystal growth, and then GaAs microcrystals were formed. During the crystal growth of the GaAs microcrystals, the V / III ratio, which is one of the growth conditions, is 30, 6
Samples different from 0, 100, 200, 300 and 400 were prepared. The growth temperature of the GaAs microcrystal is 750 ° C.

The method used for forming the GaAs microcrystals utilizes the three-dimensional growth generally referred to as SK mode growth, which is observed in the lattice-mismatched epitaxial growth. In this embodiment, GaAs _0.50 P
_{When a} crystal having a lattice mismatching ratio such as GaAs with respect to the lattice constant of the _0.50 underlying crystal in the bulk state, that is, having a different lattice constant in the bulk state is epitaxially grown, the crystal is initially grown. Is known to have a three-dimensional island shape. If crystal growth continues as it is, these island crystals will grow and coalesce,
The shape changes to a two-dimensional film. The shape and cross-sectional dimensions of the three-dimensional island crystals at the beginning of this growth and their variations,
It is known that and the density depend on the material of the semiconductor crystal, the lattice mismatch rate, the plane orientation of the base crystal, and the like. According to the present invention, in addition to this, it has been clarified that these change depending on the V / III ratio, which is one of the growth conditions when forming semiconductor microcrystals.

First, when the off-angle of the substrate was smaller than 2 °, it was observed that some of the island-shaped crystals had an amoeba shape. If the off angle of the substrate is larger than 8 °,
It was partially observed that adjacent island crystals were bonded.
These do not function as quantum boxes. Therefore, it was found that the off angle of the substrate is preferably 2 ° to 8 °. FIG. 1 is a table comparing variations in the density and size (standard deviation value) of these semiconductor microcrystals when the off-angle of the substrate is 2 °. When the V / III ratio is 100 to 200, the variation is smallest and the density is high. A quantum dot is a quantum well in which carriers are confined in zero dimensions, and the density of states function of carriers in the quantum dot becomes a delta function. Therefore, for example, when this is used for the light receiving layer of the light receiving element, other than light of energy determined by the quantum level,
That is, neither light of higher energy nor light of lower energy is ideally absorbed, so that a light receiving element having a very narrow wavelength band is realized. However, in the devices actually manufactured so far, there was a large variation in the shape of the quantum dots, the cross-sectional dimension, etc., and therefore, the narrow wavelength band was not exhibited.

Using the present invention, a light receiving element using a quantum dot structure as a light receiving layer was produced. FIG. 2 is a sectional view showing the structure. This light receiving element is an n-type GaP (10
0) 2 ° off <110> On the substrate 10, a buffer layer 11 made of n-type GaP, a base layer 12 made of n-type GaAs _0.60 P _0.40 (thickness 3 μm), i-type GaAs
_0.60 P _0.40 energy barrier layer 13 and GaA
Quantum dot structure light-receiving layer 15 (thickness 0.2 μm) made of s microcrystal 14, emitter layer 16 (thickness 0.4 μm) made of p-type GaAs _0.60 P _0.40 , window layer made of p-type GaP 17 (thickness: 0.5 μm), and the p electrode 18 and the n electrode 19 are formed. Third
The figure shows the absorption wavelength band of the above-mentioned light receiving element. In the figure, (a) shows V / III during the growth of semiconductor crystallites.
The ratio is 30 which is usually used, and (b)
Has a V / III ratio of 150. Compared to (a), (b) according to the present invention has a narrow wavelength band and high sensitivity. Although the GaAsP-based mixed crystal semiconductor was selected as the material in this embodiment, regardless of this, for example, lnGa
The present invention can be realized by using other semiconductor materials such as AsP. In addition, although the light receiving element is manufactured in the above-mentioned embodiment,
The present invention has the same effect in other semiconductor devices such as light emitting devices.

[0011]

As described above, according to the present invention, it is possible to manufacture a semiconductor device using a quantum dot structure having good characteristics.

[Brief description of drawings]

FIG. 1 is a comparison table showing the effects of the present invention.

FIG. 2 is a sectional view showing a structure of a light receiving element that is an embodiment of the present invention.

FIG. 3 is a graph showing the absorption wavelength band and sensitivity of a light receiving element that is an embodiment of the present invention.

[Explanation of symbols]

10 ... Semiconductor substrate, 11 ... Buffer layer, 12 ... N-type Ga
As _0.60 P _0.40 Base layer, 13 ... i-type GaAs
_0.60 P _0.40 energy barrier layer, 14 ... GaAs
Quantum dots, 16 ... P-type GaAs _0.60 P _0.40 emitter layer, 17p-type GaP window layer, 18 ... P electrode, 19 ... N electrode.

Claims (3)

[Claims] 1. A semiconductor microcrystal made of a semiconductor having a cross-sectional dimension about the de Broglie wavelength of an electron, and a semiconductor having a potential energy higher than that of the semiconductor microcrystal and functioning as an energy barrier. In the manufacture of a semiconductor device including a 0-dimensional quantum well that surrounds a crystal, the crystal growth is performed by a metal organic chemical vapor deposition method, and the microcrystal is formed by a lattice constant in a bulk state of the semiconductor crystal that forms the microcrystal. And a material having a lattice constant different by 1% or more in the bulk state of the semiconductor crystal forming the energy barrier, and the ratio of the group V source material supply mole amount to the group III source material supply mole amount is 100.
To 200 in the range of 200 to 200, 2. The light receiving element according to claim 1, wherein the substrate of the semiconductor element is a substrate whose plane orientation is off by 2 ° to 8 ° in the <110> direction from (100). 3. The semiconductor crystal material of the quantum dot structure comprises Al _x Ga as a semiconductor crystal forming microcrystals.
_1-x As (0 ≦ x ≦ 1) is used as a semiconductor crystal that surrounds the microcrystal and forms an energy barrier, and is GaAs _1-y P.
The light-receiving element according to claim 1, wherein _y (0.25 ≦ y ≦ 1) is used.