Analysis of magnetic field dependent Hall data in narrow bandgap Hg1−xCdxTe grown by molecular beam epitaxy

Abstract

The analysis of magnetic field dependent Hall data is presented for three representative Hg1−xCdxTe layers grown by Molecular Beam Epitaxy with x in the range 0.193 to 0.244. These samples exhibit ‘‘anomalous’’ Hall characteristics which are analyzed using a hybrid approach consisting of mobility spectrum (MS) analysis followed by a multi-carrier fitting (MCF) procedure. This hybrid approach is able to readily separate contributions to the total conductivity arising from extrinsic carriers, thermally activated intrinsic electrons, and two-dimensional electron layers. The extracted transport parameters for thermally activated intrinsic electrons are shown to be in excellent agreement with established physical models for narrow bandgap HgCdTe. The two-dimensional electron layers are found to be only weekly temperature dependent with an electron mobility in the range of 2 to 4×104 cm2/V s and a sheet density in the range of 1011 to 1012 cm−2. Of particular interest, is the fact that the ‘‘anomalous’’ Hall characteristics exhibited by all three samples are shown not to be indicative of poor-quality material. This anomalous behavior is found to be due to comparable contributions to the total conductivity from either bulk majority carrier holes and intrinsic minority electrons, or bulk majority carriers and a two-dimensional electron population. The practical aspects of implementing the MS+MCF procedure are discussed, with particular emphasis on the range of magnetic fields required for unambiguous and accurate parameter extraction.

Scattering times in AlGaN/GaN two-dimensional electron gas from magnetotransport measurements

“…The parabolic background at magnetic field larger than 2 T is due to the parallel conduction in n-AlGaN barrier. The electron sheet density and transport mobility of 2DEG can be obtained by means of two-carrier simulation process [11], taking electrons in both the barriers and wells into consideration. The resulting electron concentration is , 1.25 £ 10 13 cm 22 and mobility , 1000 cm 2 /Vs at 20 K where quantum corrections to magnetoresistance are very small.…”

Unconventional electronic phase transition in SnBi2Te4: role of anomalous thermal expansion

“…The mobilities and carrier densities are obtained from the H-dependent Hall resistivity (ρ yx ), as shown in figure S2(e) of SM. Interestingly, conductivities (σ) do not fit a twoband model [72,74], rather a three-band model [75,76] is required to correctly capture all the features. The expression for the three-band model and satisfactory global fits (see figure S2(f) of SM) of σ are shown in SM.…”

HgCdTe technology in Australia

“…Arrays of high performance implanted diodes, fabricated externally (since MRG technology was not developed yet) confirmed device quality material. The transport characteristics of p + /π/n + structure are presented in Figure 4, with properties of each layer extracted from magnetic-field dependent Hall and resistivity data using mobility spectrum technique developed at MRG to solve the problem with mix conduction [7,8]. In the mid 1990s, in spite of spectacular research and technology achievements by the scientists and engineers from DSTO/CMTEK, the climate for commercial HgCdTe in Australia, mostly due to economic reasons, started to deteriorate dramatically, and by 1994 the decision was made to stop the HgCdTe development at DSTO/CMTEK.…”