Variable magnetic field Hall effect measurements and analyses of high purity, Hg vacancy (<i>p</i>-type) HgCdTe

Abstract

This paper reports on complete Hall characterization of Hg vacancy ( p-type) HgCdTe with very high purity and compositional uniformity. The x-values of the Hg1−xCdxTe samples ranged from 0.180 to 0.300 with carrier concentrations of 6×1015 to 3×1017. Each sample was of very uniform composition with Δx&amp;lt;0.0015, as verified from room temperature infrared transmission measurements. This characterization couples variable magnetic field (up to 150 000 G) and temperature (from 15 to 160 K) data with an analysis procedure which includes heavy holes, light holes, and electrons. The measurements and analyses yield unambiguous determination of the two Hg vacancy ionization energies, one shallow level at 12–14 meV for x=0.216 HgCdTe and one deeper level at 40% of the band gap measured from the valence band edge. In addition, not only can the majority carrier (heavy holes) temperature dependent concentrations and mobilities be determined by this technique, but both the minority carrier (electron) and the light hole concentrations and mobilities have been determined as a function of temperature. At magnetic field strengths of 40 000 G and above, the heavy hole concentration was observed to decrease with increasing magnetic field. This occurred at all temperatures (15 to 160 K) investigated. This effect is commonly referred to as magnetic ‘‘freeze out’’ and is reported here for HgCdTe for the first time.