Shubnikov–de Haas oscillations on as-grown and annealed molecular-beam-epitaxy-grown Hg1−xCdxTe alloys doped with indium

Abstract

Transverse resistivity ρxx, longitudinal resistivity ρzz, and Hall resistivity ρxy on heavily indium-doped as-grown and annealed Hg1−xCdxTe (0.24<x<34) alloys in a magnetic field up to 12 T and temperature range 1.2–25 K have been measured. The as-grown and annealed samples show good quality Shubnikov–de Haas oscillations in which the effective masses m*, free-electron densities nSdH, and Dingle temperatures TD are extracted. The deduced m* and nSdH from the as-grown and annealed samples are in good agreement within 12%. However, there are considerable improvements in the low field Hall mobility μH (a maximum 54% increase) and a reduction in TD (a maximum 65% decline) in the annealed samples. Analysis at low field seems to indicate that broadening due to an inhomogeneous impurity distribution contributes to TD in addition to the partial cancellation produced by different frequencies of oscillations. An estimate of the average values of an electron density fluctuation Δn/n and its spatial extent ΔL based only on TD and Hall mobility temperature Tμ is presented. The deduced ΔL is in the order of mean free path l. This, therefore, can limit μH and the values of l and ΔL and this indicates that if there is an inhomogeneous distribution of indium donor, high-temperature annealing tends to homogenize the distribution of indium donors by diffusion.