SJ 3244.4-1989 Test method for carrier concentration profile distribution of gallium arsenide and indium phosphide materials - electrochemical voltage capacitance method SJ3244.4-1989 standard download decompression password: www.bzxz.net

Standard of the Ministry of Machinery and Electronics Industry of the People's Republic of China Test method for surface distribution of carrier concentration of gallium arsenide and indium phosphide materials - electrochemical voltage capacitance method
1 Subject content and scope of application
SJ3244.4-89
1.1 This standard specifies the principle of electrochemical voltage capacitance method, instrument and electrolyte requirements, measurement steps, and calculation of measurement results.
1.2 This standard is applicable to n-type and p-type gallium arsenide and indium phosphide with carrier concentrations of 1014~1019cm-3, and is also applicable to the measurement of surface distribution of carrier concentration of aluminum gallium arsenide and indium phosphide materials. 2 Principle
21 When the semiconductor surface contacts with a suitable electrolyte, it can form an approximate Mott-Schottky contact barrier. Although the flat band potential of different semiconductor materials and different electrolytes is different, the two sides of the contact (semiconductor material and electrolyte) will form a certain capacitance. This capacitance value is related to the carrier concentration of the semiconductor. The carrier concentration is given by the Mott-Schottky capacitance formula:
N=_2(V.-VR)c2
Where: Vp-diffusion barrier, V
VR-applied bias, V:
q-unit charge, its value is 1.602×10-19C, (i)
-semiconductor material dielectric constant, nickel arsenide is 13.18, phosphide is 12.35; 80-vacuum permittivity, its value is 8.859×10-14F/cm, A--contact area between illuminated sample and solution, cm2, N--material carrier concentration, cm-3
e--electron charge coulomb (C):
C--capacitance.
The relationship between the Mott-Schottky equation for the contact between the suitable electrolyte and the semiconductor is not affected by factors such as material concentration and preparation process. The difference of flat band potential solution mainly depends on the pH value. 2.2 At the contact point between n-type material and electrolyte, under uniform illumination of specified light intensity, select appropriate cathode dissolution potential to produce anodic dissolution. P-type material can be anodic dissolved under dark field and appropriate anodic dissolution potential. All can obtain flat corrosion pits. Achieve layer-by-layer dissolution. Measurement depth:
Approved by the Ministry of Machinery and Electronics Industry of the People's Republic of China on March 20, 1989, implemented on March 25, 1989
X=-W,+WR
SJ3244.4—89
Where: W is the depth of depletion layer. Unit μm, WR is the depth of anodic dissolution, unit μm.
Depletion layer depth
W,=ee,A/C
·（2）
（3）
The thickness of the sample dissolved is calculated by Faraday's law from the anodic dissolution current and time parameters, M
WNFPA
（4）
Where: M—moles of dissolved material, 144.63g for gallium arsenide and 145.795g for phosphide; N—electrochemical equivalent number, its value is 6;
F——Faraday constant, its value is 9.64×101Cp—density of dissolved material, 5.32g/cm3 for gallium arsenide and 4.787g/cm3 for phosphide steel. I——current.
From this, the distribution curve of carrier concentration n and depth X can be obtained. That is, the longitudinal carrier concentration surface distribution. 23 In the current-voltage curve, for n-type materials, when the anode is polarized and illuminated, a limiting current appears. When the potential exceeds a certain value, the current suddenly increases. When the anode is polarized, there is no obvious difference between light and dark, and both increase with the increase of potential. For p-type materials, it is the opposite. In the capacitance-voltage curve, a small positive bias is added to the Mott-Schottky contact. The capacitance increases. For n-type materials, the capacitance decreases. The semiconductor materials and their conductivity types are gradually identified through the current-voltage curve and the capacitance-voltage curve.
3 Measurement device and electrolyte
3.1 Homemade measurement device
3.1.1 The schematic diagram of the measurement device is shown in Figure 1. Mathematical
PTFE electrolytic cell
Electrolytic cell
Lamp line power supply
Digital electric
Constant potentiostat
Sample implant cathode
PV diffused connection device Capacitor
Carbon cathode cabinet
Long diagram
Electrolyte inlet
Figure 1 Electrochemical C-V method measurement device
3.1.2 Sample stage and electrolytic cell
The sample to be measured is a copper-coated tin probe, which is pressed on the polyvinyl chloride annular contact area limiter of the electrolytic cell. The sample maintains a constant area contact with the electrolyte. The diameter is about 1.8mm. The graphite cathode and the probe constitute the anode dissolution path. 3.1.3 Digital voltmeter
Measure the dissolution potential relative to the reference electrode (S, C, E). The range is 0~2V. The sensitivity is better than 1mv, and the input 2-bZxz.net
The impedance is greater than 100M9
3.1.4 Capacitance meter
SJ3244.489
Used to measure the capacitance between the two electrodes of the platinum auxiliary cathode and the probe. The measuring range is 20～20000pf, with an accuracy of 5%. The capacitance test frequency of arsenide material is 100kl1z, the signal amplitude is 100mv (rm, s), and the capacitance test frequency of phosphating steel material is 100Rz or 3RHz.
3.1.5 Light source
Use a focused and uniform hook to irradiate the sample. Quartz halogen tungsten lamp, power is 100W, 3.1.6 Constant potential instrument
Current -500mA
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