Magneto-Transport Characterizations Of Two-Dimensional Electron Gas In Ⅲ-ⅤSemiconductor Heterostructures

Magnetoresistances of III-V semiconductor heterostructure materials in deep low temperature under high magnetic field were studied. The information of two-dimensional electron gas(2DEG) which was useful to future application was achieved. The obtained results in this dissertation are as follows:l.The magneto-transport measurement was applied to Hall bar samples of Ino.65Gao.35As/Ino.52Alo.48As quantum well in the low temperature range (1.5-1OK) and magnetic field from0T up to10T. Then obvious magnetoresistance oscillations and beating patterns were observed. Electrons occupied two subbands, and beating patterns were due to the spin-splitting of the first subband. The effective masses for spin-up and spin-down electrons of the first subband are m+=0.047m0,m=0.045m0, respectively. The Rashba spin-orbit(SO) constants for spin-up and spin-down electrons of the first subband are a+=8.09x1013eVm,α=8.64x10-13eVm, respectively, which are an order of magnitude smaller than the result obtained with normal method(α=6.45x10-12eVm), so that SO constants are not major factors of spin-splitting energy at this time.2. The magnetotransport measurement was performed on a GaN/AlxGa1-xN heterostructure sample in the low temperature range (1.4-25K) and at magnetic field from0T up to13T. Magnetoresistance of2DEG confined in the heterostructure was investigated. The negative magnetoresistivity in the whole magnetic field range is induced by electron-electron interactions(EEI), while the positive magnetoresistivity in the high field range results from the parallel conductance. In consideration of EEI and parallel conductance, we got the mobility of first subband (μ1=0.37m2/Vs), as well as the concentration (n2=9.7x1015m-2) and the mobility(μ2=0.029m2/Vs) of the parallel channel at1.4K by means of fitting experimental data. Further more, another method of calculation was carried out to check their accuracy.