JPH08316586A - Method for measuring dislocation density of ii-vi compound semiconductor single crystal - Google Patents

Abstract

PURPOSE: To obtain a method for directly measuring the dislocation density on the (100) face of a II-VI compound semiconductor crystal including ZnSe being expected as a material of blue light emission device. CONSTITUTION: A II-VI compound semi-conductor crystal is sliced on the (100) face thereof to obtain a single crystal substrate of ZnSe, for example, which is then subjected to surface polishing and mirror face etching. The ZnSe substrate 5 is placed in a Teflon basket 2 which is then set into 0.1vol.% bromine methanol solution 6 in the reaction bath 1 of a single crystal substrate etching system. Subsequently, etching is performed by turning a stirrer 3 disposed on the bottom of the reaction bath for a predetermined time by means of a magnetic stirrer 4. The ZnSe substrate is then observed by means of a Nomarski microscope and the dislocation density is measured from a clear etching image thus obtained.

Description

Detailed Description of the Invention

[0001]

The present invention relates to II-V such as zinc selenide (ZnSe), which is expected as a material for blue light emitting devices.
The present invention relates to a method for measuring dislocation density in a Group I compound semiconductor single crystal.

[0002]

2. Description of the Related Art Zinc selenide (ZnSe), which is one of the II-VI group compound semiconductors, has been conventionally manufactured by a vapor phase growth method or a high pressure melting method. It is crystallographically incomplete and contains an incomplete part in the crystal called a dislocation. The number of dislocations per unit area is called a dislocation density, which is closely related to the emission lifetime of blue light emitting devices and is very important in determining whether or not it is suitable as a substrate for epitaxial growth. It is one of the characteristics.

Up to now, the methods for measuring the dislocation density of ZnSe single crystals have been (111) planes and (110) planes of single crystals.
Although a method for measuring the plane is known, a method for measuring the (100) plane is not yet known, and even when the crystal orientation for epitaxial growth is the (100) plane, a single crystal substrate coordinated to the orientation is known. It was not possible to directly obtain information on dislocation density from.

Therefore, for example, there are two kinds of slices, that is, the orientation of the epitaxial growth substrate and the orientation of the single crystal for dislocation density investigation from the large diameter and long bulk crystal obtained by the high pressure melting method. Was needed.

[0005]

As described above, since the conventional dislocation density measuring method cannot directly measure the dislocation density on the (100) plane, for example, a ZnSe single crystal substrate (1
In the case of performing epitaxial growth on the (00) plane, there is a drawback that it cannot be determined in a short time whether or not the substrate can be used as the substrate itself.

Therefore, an object of the present invention, including ZnSe expected as a material for a blue light emitting device, is II-VI.
It is another object of the present invention to provide a method for directly measuring the dislocation density on the (100) plane of a group compound semiconductor crystal.

[0007]

DISCLOSURE OF THE INVENTION As a result of intensive studies to achieve the above object, the inventors of the present invention have found that when a (100) plane of a ZnSe single crystal substrate is etched using a dilute bromine methanol solution, dislocation portions are generated. Since a clear etched image can be obtained, the dislocation density can be measured, and further, the present invention was found to be applicable to II-VI group compound semiconductor single crystals other than ZnSe single crystals, and the present invention was reached.

That is, according to the present invention, a substrate obtained by slicing the (100) plane of a II-VI group compound semiconductor single crystal is subjected to surface polishing and mirror surface etching, and then immersed in a bromine methanol solution. The present invention provides a method for measuring dislocation density of a II-VI group compound semiconductor single crystal body, which comprises etching and measuring dislocations on the (100) plane from the obtained etched image.

[0009]

A ZnSe single crystal substrate used as a raw material in the present invention is obtained by first growing a ZnSe polycrystal by a high pressure melting method as a seed crystal on the seed crystal using a vertical Bridgman furnace or a vertical annealing furnace to obtain a single crystal. . That is, in the former, the crucible containing the melt was lowered in an electric furnace with a temperature gradient to grow crystals, and in the latter, the crucible was placed in an electric furnace with a vertical temperature gradient and the temperature gradient was maintained. Gradually cool and grow crystals from the bottom of the crucible.

Next, this single crystal was sliced with a slicer (10
It is obtained by polishing the product cut in the 0) direction by lapping performed by interposing free abrasive grains, and then mirror-finishing the surface for mirror-finishing and cutting the product into a predetermined shape.

In the present invention, the surface of the substrate is etched by immersing the single crystal substrate in a 0.1% by volume bromine-methanol solution. The etching condition is room temperature for about 80 to 150 seconds while stirring the solution. Since a clear etched image can be obtained by immersion, the dislocation density can be measured from this.

[0012]

EXAMPLE FIG. 1 is a schematic sectional view showing a single crystal substrate etching apparatus used in this example, and FIG. 2 is a micrograph showing a corroded portion after etching a ZnSe single crystal substrate. ) Is 4
00 times and FIG. 10B are magnified 1000 times, which will be described below with reference to these figures.

Z previously obtained by the high pressure melting method
A (100) plane was sliced from the nSe single crystal to cut a 5 mm square × 1 mm thick substrate, the surface of the substrate was polished, and then mirror-etched.

Reaction tank 1 of the single crystal substrate etching apparatus shown in FIG.
The ZnSe substrate 5 was placed in a Teflon basket 2 so that it was immersed in a 1 vol% bromine methanol solution 6 at room temperature (about 20 ° C.) and placed in a reaction tank.

A stirrer 3 is previously provided at the bottom of the reaction tank, and the stirrer 3 is rotated at a speed of 250 rpm for 120 seconds by a magnetic stirrer 4 at the bottom of the reaction tank.
The etching process was performed.

The etched ZnSe substrate was taken out from the reaction tank, ultrasonically washed in methanol and dried, and then the corroded portion (dislocation portion) was observed with a Nomarski differential interference microscope.

The observed dislocations on the ZnSe substrate are shown in FIG.
The dislocation density per unit area can be easily measured from these photographs, which are shown as photographs of 400 times of (a) and 1000 times of (b).

An etching treatment was also attempted on II-VI group compound semiconductor single crystals other than ZnSe, but almost the same results as in the case of ZnSe were obtained.

[0019]

As described above, there is no conventional means for directly measuring the dislocation density on the (100) plane of a II-VI group compound semiconductor single crystal, but the method of the present invention provides a simple apparatus. The dislocation density on the (100) plane can be measured in a short time because it is possible to measure the dislocations that are clearly defined by etching the (100) plane with the use of the II-VI semiconductor as an epitaxial growth substrate. Can be judged easily.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a single crystal substrate etching apparatus used in Examples.

FIG. 2 is a micrograph showing a corroded portion after etching a ZnSe single crystal substrate, (a) is 400 times and (b) is 1000 times.
It is a double magnified photo.

[Explanation of symbols]

 1 Reactor 2 Basket 3 Stirrer 4 Magnetic Stirrer 5 ZnSe Substrate 6 Bromine Methanol Solution

Claims (1)

[Claims] 1. A group II-VI compound semiconductor single crystal (10
The substrate obtained by slicing the (0) plane was subjected to surface polishing and mirror-etching treatment, and then etched by immersing it in a bromine-methanol solution. From the obtained etched image, dislocations on the (100) plane were obtained. II-V characterized by measuring
Method for measuring dislocation density of group I compound semiconductor single crystals.