The topological insulator HgTe - grown on GaAs substrates

In the past few years MBE-grown HgCdTe/HgTe heterostructures have revealed to be suitable systems to study the magnetotransport properties of both two-dimensional topological insulators with spin polarized edge channels and just recently of three-dimensional topological insulators. In this work we present the successful change of substrate material. So far, growth has been carried out on either CdTe or CdZnTe, with both systems being limited with respect to wafer size and pricing. By growing a ZnTe/CdTe heterostructure on GaAs substrates, we were able to prepare a high-quality <001> CdTe surface, as revealed by RHEED, AFM and HRXRD measurements. The subsequently grown HgCdTe/HgTe quantum-well systems showed carrier mobilities comparable to such grown on commercial CdTe substrates. The new material system allows not only a much higher yield in working wafer size per growth run, but offers also new possibilities with respect to backgating, doping and lattice-matching and avoids the problematic wet-etching needed to prepare CdTe and CdZnTe prior to growth.