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A study was conducted on the electrical properties of subbands in the accumulation layers of the alloy semiconductor Hg1-xCdxTe. Quantitative mobility spectrum analysis (QMSA) and Shubnikov-de Haas oscillation measurements were employed to identify the concentration and mobility all types of subband carriers. Results demonstrate the capability of QMSA to generate accurate electric parameters without using complex semiconductor energy bands.

Spin splitting of the two-dimentional electron gas (2DEG) in modulation-doped Al[sub 0.22]Ga[sub 0.78]N/GaN heterostructures has been studied by means of magnetotransport measurements at low temperatures and high magnetic fields. The spin splitting is observed in Shubnikov–de Haas oscillations at a magnetic field higher than 5.4 T and a temperature of 1.4 K. The effective g factor g[sup *] is enhanced due to the exchange interaction of the 2DEG at high densities. The ratio of the transverse effective g factor g[sub ⊥][sup *] and the longitudinal effective g factor g[sub ∥][sup *] is g[sub ⊥][sup *]/g[sub ∥][sup *]=2.6 indicating the large difference between g[sub ∥][sup *] and g[sub ⊥][sup *]. It is demonstrated that the anisotropy of the g[sup *] is due to the strong polarization-induced electric field at the heterointerface. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The strong spin-orbit (SO) interaction in a gated high-mobility [In.sub.0.53][Ga.sub.0.47]As/InP quantum well two-dimensional electron gas is described, where the SO interaction is dominated by the Rashba mechanism. The Rashba coupling parameters determined from analysis of both weak antilocalization and the beating pattern in the Shubnikov-de Haas oscillations have agreed well and the small difference between them is described by a magnetic-field-dependent effective g factor.

The magnetotransport properties of a gated [In.sub.0.53][Ga.sub.0.47]As/InP quantum well structure are studied in the presence of spin splitting when only one electronic subband is occupied. The studies have shown that larger quantum mobility is found for the higher-energy spin subband and the difference between the quantum mobilities for the two spin subbands is altered with the gate.

The magnetotransport measurements before and after illumination are employed to explore the weak antilocalization (WAL) effects of the two-dimensional electron gas (2DEG) in high mobility [Al.sub.x][Ga.sub.1-x]N/GaN heterostructure as well as beating patterns in the Shubnikov-de Haas (SdH) oscillatory magnetoresistance. The results showed that the zero-field spin splitting energy associated with the Rashba effect has decreased after illumination.

Magnetointersubband scattering (MIS) oscillations of two-dimensional electron gas (2DEG) in Al[sub 0.22]Ga[sub 0.78]N/GaN heterostructures have been investigated by means of magnetotransport measurements at low temperatures and high magnetic fields. Double periodic Shubnikov–de Haas oscillations modulated by MIS oscillations have been observed due to the intersubband scattering of the 2DEG at the two lowest subbands in the triangular quantum well at the heterointerface. By using the fast Fourier transform analysis, it is found that the MIS oscillations become slightly weaker with an increase in temperature. From the MIS frequency, the energy separation between the first and the second subbands is determined to be 80 meV. The observation of the MIS effect indicates that the effective masses of the electrons in the first and second subbands are the same in Al[sub 0.22]Ga[sub 0.78]N/GaN heterostructures. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]