MBE Growth of Strained HgTe/CdTe Topological Insulator Structures.

We present molecular beam epitaxy growth of tensile-strained HgTe/CdTe thin films for realization of three-dimensional (3D) topological insulator structures. The growth temperature is investigated by looking at crystal quality using high-resolution x-ray diffraction, being found to be much lower than the usual surface temperature for low-cadmium-fraction HgCdTe material. The strain status of HgTe is checked as a function of thickness, and the first indication of strain relaxation is found to appear for thickness well below the critical thickness expected for this system. Surface and interface morphology are also investigated, and well-defined interfaces as well as atomically flat surfaces are demonstrated. Finally, transmission electron microscopy is used to image the material structure of a HgCdTe/HgTe/HgCdTe stack suitable for electronic transport experiments. [ABSTRACT FROM AUTHOR]