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Electron charge and spin ambipolar transport testing method of transmission grating-modulated pumping-detection spectrum

A technology of transmission grating and test method, applied in the direction of polarization influence characteristics, etc., can solve the problems of complex experimental device, difficult and high spatial resolution, large amount of test data, etc., and achieve the effect of simple experimental test device and high sensitivity

Inactive Publication Date: 2010-08-04
SUN YAT SEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the experimental devices of these methods are relatively complicated, requiring time and space two-dimensional scanning system, the amount of test data is also large, and it is difficult to obtain a small focused spot, so it is difficult to achieve high spatial resolution
More importantly, none of these methods can measure the mobility at the same time to verify the validity and effective conditions of the Einstein relationship

Method used

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  • Electron charge and spin ambipolar transport testing method of transmission grating-modulated pumping-detection spectrum
  • Electron charge and spin ambipolar transport testing method of transmission grating-modulated pumping-detection spectrum
  • Electron charge and spin ambipolar transport testing method of transmission grating-modulated pumping-detection spectrum

Examples

Experimental program
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example 1

[0020] Example 1 Electron charge bipolar transport constant test of GaAs

[0021] The schematic diagram of the experimental device is as figure 1 As shown, but the 1 / 4 wave plates 2 and 3 are removed, that is, the pump beam 4 and the probe beam 5 are both linearly polarized. The femtosecond laser pulse width is about 150fs, the center wavelength is 850nm, and the pulse repetition rate is 90MHz. The focal length of the focusing lens 6 is 50mm. Set the average power of the femtosecond pump beam 4 to 6.4 mW, and the pump / probe beam power ratio is about 3. First, the transmission grating 7 is removed to test the recombination decay kinetics of the electrons excited by the pump pulse, as figure 2 Shown in curve 1. Then, put back the transmission grating 7, and test the recombination and diffusion decay kinetics of the electron grating excited by the pump pulse, such as figure 2 Curve 2 is shown in the hollow box. Comparing curves 1 and 2, the decay rate of 2 is significantl...

example 2

[0023] Example 2 Measurement of Electron Spin Polarized Bipolar Transport Constant in GaAs

[0024] The schematic diagram of the experimental device is as figure 1 As shown, both the pump beam 4 and the probe beam 5 are circularly polarized light. The femtosecond laser pulse width is about 150fs, the center wavelength is 850nm, and the pulse repetition rate is 90MHz. The focal length of the focusing lens 6 is 50mm. Set the average power of the femtosecond pump beam 4 to 6.4 mW, and the pump / probe beam power ratio is about 3. First, remove the transmission grating 7, and set the pump and probe pulses to have the same circular polarization handedness, and test the recombination decay dynamics of the spin-polarized electrons excited by the pump pulse, as image 3 Shown in curve 1. Then, put back the transmission grating 7, repeat the same test, and get image 3 Middle curve 2. Comparing curves 1 and 2, 2 decays significantly faster than 1, showing the obvious role of diffus...

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Abstract

The invention relates to a testing method of transmission grating-modulated pumping-detection saturated absorption spectrum. The method is characterized in that black / white transmission grating-modulated pump light is used before a sample to generate period matrix intensity distribution grating, replace the traditional grating formed by two beam interference and stimulate the electronic grating with period matrix concentration distribution in the sample; the saturated absorption change of detection light is used to replace the traditional grating diffraction signal intensity change so as to measure the attenuation kinetics of instantaneous electron concentration grating. The method has the advantages of high sensitivity, simple experiment device and the like. The experiment device schematic diagram is shown in the drawing 1 of the abstract and can be used to measure the ambipolar diffusion constant of electron spin; and when an electric field is exerted on the sample along the vertical direction of grating stripe, the ambipolar diffusion constant and mobility of electron spin can be measured at the same time. When 1 / 4 wave plate 2 and 3 are removed, the ambipolar diffusion constant and mobility of electron charge can be measured. The beneficial effects of the invention can be shown when used in the testing example of GaAs semiconductor.

Description

technical field [0001] The invention relates to an optical test method for the bipolar transport of electron charges and spins. Its characteristic is to use the transmission grating to modulate the spatial distribution of the pulse excitation light intensity, and to excite the electrons with a periodic concentration distribution in the sample; then use another weak pulse light to pass through the grating to detect the decay dynamics of the periodic distribution electrons; apply the developed Fitting the decay kinetics to a theoretical model yields the ambipolar diffusion constant and mobility of the electron's charge and spin. It has important application value in the field of semiconductor testing and scientific research. Background technique [0002] The charge and spin transport of electrons is an important way of information transmission in semiconductors. The two physical quantities that determine the transport velocity are the diffusion constant and the mobility. Th...

Claims

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Application Information

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IPC IPC(8): G01N21/21
Inventor 赖天树张秀敏陈科陈达鑫
Owner SUN YAT SEN UNIV
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