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.