| The magnetoresistance oscillations of semiconductor heterojunction two-dimensional electron gas(2DEG) originate from electron quantum effect, which reflecting the state density variation of Landau energy at Fermi level. We can study the magnetoresistance oscillations of two-dimensional electron gas by magnetotransport measurement, by which we can get abundant electrical character and electrons-subband property. We systematically investigate magnetoresistance oscillations of heterojunction two-dimensional electron gas for different material by Shubnikov-de Haas(SdH) effect measurement and normal vary magnetic-field Hall measurement under very low temperature and high magnetic-field, and adopt fast Fourier transform, as well as combine quantitative mobility spectrum analysis and multi-carrier fit, then obtain the following results:1. The magnetoresistance oscillations caused by electron intersubband scattering, as well as the two subbands occupied by two-dimensional gas in AlGaN/GaN heterojunction interface have been observed, which is independent of the temperature, difference from SdH oscillation. And striking beating patterns in magneto-resistance vs magnetic field are observed in the vicinity of a special temperature. Theoretical simulation is performed and the comparison between numerical simulations and the experimental data reveals that the beating patterns are due to the interference of the magneto-intersubband scattering and the SdH oscillator of first subband.2. The magnetoresistance oscillations of AlGaN/GaN heterojunction two-dimensional gas represent the vary of first positive and then negative, analysisindicate that which is coming from quantum coherent scattering in AlGaN/GaN heterojunction two-dimensional gas and express as electrons weak anti-localization and localization effect. According to the theory given by Hikami, Larkin and Nagaoka that relation of magnetic conductivity with the varying of magnetic field under diffusion approximation, we fitting results of experiments and get spin-orbit scattering time and inelastic scattering times. Spin-orbit scattering of electrons is mainly coming from spin-splitting induced by crystal-field, which is independent from the lattice temperature, while the inelastic scattering time is found to follow the inverse relation with temperature, which indicate that electron-electron scattering with small energy transfer is the dominant inelastic process.3. We detailed study the beating oscillation in Shubnikov-de Hass (SdH) of magnetic two dimensional electron gas consisting of a modulation doped n type Hg0.82Cd0.16Mn0.02Te/Hg0.3Cd0.7Te first type quantum well, by which found that temperature, gate voltage are both bring the variety of magnetic resistance beating node position. By analyzing beating patterns, gate voltage dependent Rashba spin-orbit splitting can be separated from temperature dependent giant Zeeman splitting.4. Shubnikov-de Haas(SdH) effect and the Hall effect of the In0.53Ga0.47As/In.52Al0.48As single quantum well with two subbands occupation have been studied, and have obtained the electron concentration, mobility, effective mass and energy levels respectively. The concentration of the two subbands deduced by Mobility Spectrum and Multi-Carrier Fitting(MS+MCF) is well consistent with the result from the SdH oscillation. It is observed that there is a frequency of f1-f2 insensitive to the temperature, as well as the frequencies of f1, f2 for the two subbandsand the frequency doubling 2fi dependent of the temperature from Fast Fourier Transform(FFT) for d2 P /dB2—1/B, it is because that the electrons have the same effective mass in different subbands and then the magneto-intersubband scattering between the two subbands has taken place strongly.
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