SJ 3244.2-1989 Measurement method of lattice mismatch between gallium arsenide, indium phosphide substrate and heterojunction epitaxial layer SJ3244.2-1989 standard download decompression password: www.bzxz.net

Standard of the Ministry of Machinery and Electronics Industry of the People's Republic of China Method for measuring lattice mismatch between gallium arsenide and indium phosphide substrates and heterojunction epitaxial layers
Subject content and scope of application
SJ3244.2—89
This standard specifies the measurement principle, steps and calculation method of lattice mismatch between heterojunction epitaxial layers and substrates. This standard applies to the following scope: The crystal orientation deviation of the epitaxial layer surface is less than 1.5. The total thickness of the multi-layer epitaxial layer is not more than 10μm. 2 Reasoning:
2.1 Principle of the structure of the double crystal goniometer
The structure of the double crystal goniometer is shown in Figure 1.
Figure 1 Schematic diagram of the double crystal goniometer
M-X-ray tube: S, S2-horizontal slit; S3-vertical slit, A-standard crystal, B-sample crystal, G-counting tube, N-recording system.
After being collimated by the slits S1, S2, and S3, the X-rays are directed to the standard crystal A. The standard body A is adjusted to the diffraction position and then fixed. It is required that only the Kαi rays in the copper characteristic radiation CuKa are directed to the sample B to be tested. The sample is adjusted to its diffraction position and then the sample is automatically rotated at a small angle in its diffraction position (the axis of rotation is the normal of the plane formed by the incident ray and the reflected ray). As the sample rotates, the counter tube will receive the diffraction line with varying intensity and send it to the recorder to draw a curve of the X-ray intensity changing with the rotation angle α of the sample, which is called the swing curve (see Figure 2b) 2.2 Principle of lattice mismatch measurement
The machine of the People's Republic of China was approved by the Ministry of Electronics Industry on March 20, 1989 and implemented on March 25, 1989
SJ3244.2---89
The lattice constant of the epitaxial layer is different from that of the substrate, which is called lattice mismatch. If the lattice constant of the epitaxial layer is different from that of the substrate, it is called lattice mismatch. The constant is αep1, and the lattice constant of the substrate is αsub. The lattice mismatch is expressed as aepl-csub-
. A beam of X-rays is irradiated onto the epitaxial wafer sample. Generally, the X-rays will pass through the epitaxial layer to reach the substrate. When there is a slight difference in the lattice constants of the epitaxial layer and the substrate, according to the Bragg law, the epitaxial layer and the substrate will produce different diffraction peaks at different Bragg angles on the swing curve. The angle difference △α between the two peaks is composed of two parts: Aa=9
, where: △ - epitaxial layer and substrate The diffraction angle difference caused by the difference in lattice constants; the diffraction angle difference caused by the tilt angle between the epitaxial layer and the substrate in △, (2).
From the △ (, α2 of the sample at two different positions, △0 and △9 can be calculated, and then the lattice mismatch can be calculated from △. Since the horizontal axis of the loop curve is the angle, the calculated △9 is actually the tilt angle between the epitaxial layer and the substrate. Figure 2 shows the measurement principle. 1
Epitaxial layer
(a) Epitaxial The main diffraction is produced when the layer and the backing sound
The sample rotates at an angle α
(b) The double-crystal pendulum appears
Figure 2 Schematic diagram of lattice mismatch measurement
3 Instruments and measurement conditions
3.1 Instruments
a, ordinary X-ray generator (host). b, X-ray double crystal goniometer.
3.2 Measurement conditions
Use Cuka1 radiation. Point focus. The double crystal (+-) is arranged in parallel. The standard crystal is a dislocation-free single crystal that has been mechanically polished and Chemically polished to a mirror surface. The crystal orientation deviation is within 10°. Use an appropriately narrow slit combined with a standard crystal. Only Kα1 is incident on the sample crystal, and both crystals take symmetrical reflections. 4 Test steps bzxZ.net
4.1 Carefully adjust the double crystal goniometer according to the operating procedures, accurately adjust the standard crystal to the diffraction position and fix it, and use a counter tube to check whether Kαl and Kα2 are separated.
SJ3244.2-89
4.2 Place the sample to be tested on the goniometer sample holder. Adjust the sample so that It is in the diffraction position, and then rotates automatically, draws a swing curve, and measures the angle difference △α between the substrate reflection peak and the epitaxial layer diffraction peak. 4.3 Rotate the sample 180 degrees around the surface normal, repeat the operation in 4.2, and measure △a2. Note: If there is no or no consideration of the tilt angle between the substrate and the outer layer, only irrigate once, and then α=α. 5 Calculation of test results
5.1 α△α2 obtained from the two measurements is calculated according to the following formula △ and △:0=（Aα,+Aα2)/2.
=（αAα2)/2.
5.2 Calculate the lattice mismatch from Ae:
△a=-（cote△0/radian）
wherein is the Bragg angle of the sample crystal, which can be found in the following table: Table: Bragg angles of some low-index surfaces of gallium arsenide and indium phosphide (body) CuKat, X=1.5705A
h, k, 1
ammonium arsenide
(a=5.6534A)
13°39
22°40
26°524
33°2-
41°52
(dm5,869A)
21°44
25°47
31°40°
34°53'
40°1°
（3）
5.3GaInAsP/InP heterojunction laser calculation example: (100) phosphating steel sample takes (400) reflection. imp=5.869A, Qimm=31°40. coto=1.6212. In fact, 1\5×10-6 radians, △0 is substituted in seconds, then (5) is simplified to: Aa=-8.1x10-6e (seconds)
5.4 The typical swing curve is shown in Figure 3
SJ3244.2-89
Sample rotation angle α (seconds)
(a) The epitaxial layer and the base are matched
The diffraction peaks are combined (two measurements)
Sample rotation angle a (seconds
e) There are two heterogeneous outer layers, both of which are mismatched and three peaks appear (one measurement)
The product rotation angle α ( sec)
(b) Typical mismatch curve
(twice loading)
Sample rotation angle 4 (sec)
(d) There is a longitudinal composition gradient in the epitaxy, and the epitaxy peak becomes broad (one false test)
Figure 3 Typical swing curve
6 Report
The test report should include the following:
a, sample source and number,
SJ3244.2—89
Calculation results of lattice mismatch -α-;
Analysis of epitaxial layer quality based on the shape of the twin crystal swing curve; c.
d. Test date and tester.
7 Accuracy
The accuracy of this method in measuring lattice mismatch is 0.005%. Additional notes:
This standard was drafted by the Thirteenth Research Institute of the Ministry of Machinery and Electronics Industry. The main drafter of this standard:
Sun Biyun
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