JPH01117016A - Hetero structure forming method - Google Patents

Abstract

PURPOSE:To enable sharp substrate temperature control, and form high quality hetero structure, by a method wherein a first semiconductor material is subjected to crystal growth by resistor heating method, and a second semiconductor material is subjected to crystal growth by resistor heating method and infrared ray irradiation. CONSTITUTION:A cleaned InP (001) substrate 4 is mounted on a substrate holder 3 in a growth chamber 1. The substrate 4 is irradiated with infrared rays by opening a shutter 54 in front of an infrared ray lamp 6. In order to form InGaAs quantum well, shutters 53, 54 of Al and infrared rays are closed, and at the same time, a shutter 52 in front of a Ga molecular beam source 22 is opened. In this state, InGaAs is grown in thickness up to 100Angstrom at a substrate temperature of 550 deg.C. Again, the shutter 52 of Ga is closed, and shutter 53 of Al and shutter 54 of infrared rays are opened. In this state, InAlAs is grown in thickness of 100Angstrom at 580 deg.C. By repeating 20 cycles of this process, a multi-quantum well structure is formed. Thereby enabling steep substrate temperature control, and forming high quality hetero structure.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for forming a heterostructure, and particularly to a method for forming a high-quality heterostructure by molecular beam epitaxy (hereinafter referred to as MBE). .

[Prior Art] In the growth of different types of semiconductor crystals, the optimum growth conditions for each semiconductor crystal are usually the same.

In particular, growth temperature plays an important role in growing a high quality epitaxial layer. Conventionally, the method used to grow semiconductor crystals with different optimal growth temperatures is to adjust the substrate temperature to the respective optimal growth temperature by controlling the power input to the heater heating method ( Journal of applied phys
ics), 52, (1981), 3861).

[Problems to be Solved by the Invention] However, the conventional method of controlling the substrate temperature by heating with a heater has the disadvantage that a steep profile of temperature change cannot be realized. This is because the heater heating method is an indirect temperature control method in which the substrate holder holding the substrate is heated and the heat is transferred to the substrate, thereby changing the substrate temperature. For this reason, when growing a multilayer structure of ultra-thin films grown at different growth temperatures, changes in the substrate temperature cannot follow changes in the material being grown, making it difficult to form a high-quality heterostructure.

An object of the present invention is to provide a method for forming a high-quality heterostructure that solves the conventional problems as described above.

Means for Solving the Problems] The present invention provides a first step of crystal-growing a first semiconductor material on a substrate at a first growth temperature controlled by a heater heating method in a molecular beam epitaxy method; a second step of rapidly controlling substrate humidity to a second growth temperature higher than the first growth temperature by using the heater heating method and irradiating infrared rays onto the substrate to grow crystals of the second semiconductor material; , a method for forming a heterostructure, characterized in that the above two steps are performed consecutively.

[Function] When a substrate is irradiated with infrared rays, lattice vibration absorption occurs and the temperature of the substrate can be increased. Unlike the indirect temperature raising process using the heater heating method, this temperature raising process can directly warm the substrate, so when used in combination with the heater heating method, an extremely steep temperature change profile can be obtained.

[Example code] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of an MBE apparatus used in the method of the present invention. Here, an example will be described in which a multiple quantum well structure in which an InGaAs quantum well is sandwiched between InMAs barrier layers is formed on an InP substrate.

First, InP(001) was chemically cleaned using the usual method.
The substrate 4 is mounted on the substrate holder 3 in the growth chamber 1.

Prior to growth, the surface of the InP substrate 4 is thermally cleaned under an As pressure of 2.5×10−5 Torr. Usually 51
At 0°C, the surface oxide film falls off and the surface becomes clean. The substrate temperature is stably controlled to the InGaAS growth temperature of 550° C. by heating with a heater.

First, in order to grow a cladding layer of InMAs,
, H molecular beam source 21.23 front shutter 51,
53, and then close the shutter 5 in front of the infrared lamp 6.
4 and irradiates the substrate with infrared rays to adjust the substrate temperature to InMA.
The temperature is raised to 580°C, which is the S growth temperature. The thickness of the grown film at this time was set to 0.5.

Next, a method for forming a multiple mother-child well structure of InGaAS and InMAs will be described. FIG. 2 is a diagram showing the substrate temperature profile and shutter control during the formation of multiple quantum wells. As shown in the figure, following the growth, M and infrared shutters 53 and 54 are closed at the same time to form the InGaAS quantum wells. Shutter 52 in front of Ga molecular beam source 22
100 layers of InGaAs were grown at a substrate temperature of 550°C. Next, the Ga shutter 52 is closed again, the N and infrared shutters 53 and 54 are opened, and InMAs is
100 people grow at ℃. This process was repeated 20 times to form a multiple quantum well structure. Finally, an InMAs cladding layer was grown again for 0.4 times.

FIG. 3 shows the photoluminescence (hereinafter referred to as PL) spectrum at room temperature of the multiple mother-child well formed in this manner. In the figure, the solid line indicates the case formed by the method of the present invention, and the broken line indicates the case formed by the conventional method.

As can be seen from Fig. 3, it is possible to control the growth temperature more accurately and steeply than with the conventional heater heating method, so it is possible to reduce the number of non-emissive centers in each layer, and as a result, a strong P[emission intensity can be obtained. Ta.

As described above, according to the present invention, a hetero quantum well structure with high luminous efficiency can be obtained.

In the above embodiments, InGaAs/InMAs
Although a hanging well is taken as an example, the method of the present invention can also be applied to material systems with different growth temperatures to form a heterostructure with high luminous efficiency.

[Effects of the Invention] As explained above, according to the heterostructure forming method of the present invention, extremely steep substrate temperature control is possible. As a result, it is now possible to form high-quality heterostructures even with material systems that were previously thought to be impossible to combine due to vastly different growth conditions, increasing the degree of freedom in material selection in device design. be able to.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of the MBE apparatus used in the method of the present invention, FIG. 2 is a diagram of the substrate temperature profile and shutter control during the formation of multiple quantum wells, and FIG. 3 is a diagram of the multiple quantum wells formed by the method of the present invention. FIG. 3 is a diagram showing a PL spectrum diagram at room temperature in comparison with a conventional example.

Claims (1)

[Claims] (1) In the molecular beam epitaxy method, a first step of growing crystals of a first semiconductor material on a substrate at a first growth temperature controlled by a heater heating method, and applying infrared rays to the substrate using the heater heating method. The second growth temperature is steeply higher than the first growth temperature.
and a second step of controlling the substrate temperature to a growth temperature of 100% and growing crystals of a second semiconductor material, the method comprising: performing the above two steps in succession.