Strain and orientation effects in mercury cadmium telluride grown by molecular beam epitaxy

摘要

Quantitative mobility spectrum analysis of variable magnetic field Hall measurements is a proven technique for determining the mobility, type and concentration of multiple charge carriers in semiconductor materials. When applied to mercury cadmium telluride, the technique often generates spurious results, the origin of which is under investigation in this work. An underlying assumption of Hall measurements in the Van-der-Pauw configuration is that conduction in the sample is laterally isotropic. To test this assumption, several six contact Hall bars have been fabricated on a sample of HgCdTe grown by molecular beam epitaxy. The Hall bars are aligned with significant crystallographic directions on the (211) oriented surface. X-ray reciprocal space maps of the same sample have been measured to quantify the strain state and orientation of the epilayers. Nomarski contrast microscopy of the sample surface reveals surface undulations on the sample, aligned with the intersection of {111} slip planes and the (211) surface. Results of mobility spectrum analysis show no significant differences with respect to the orientation of Hall bars in the heavily doped sample under investigation.