Molecular-beam-epitaxial growth and characterization of In2Te3

Abstract

We report studies of the molecular-beam-epitaxial growth of In2Te3. The unique structure of In2Te3, with 1/3 of the In sublattice sites vacant, is of fundamental interest for molecular-beam-epitaxial growth dynamics. We show that thin-film (500–7000 Å) single-crystal In2Te3 can be grown successfully on InSb(100) homoepitaxial layers at substrate temperatures of 300–350 °C and Te/In flux ratios of 3/2 to 5/2. Epitaxy has been monitored by reflection high-energy electron diffraction and the stoichiometry of the grown layers assessed by Auger spectroscopy and energy dispersive x-ray analysis. Raman studies of the layers are presented and compared with a bulk In2Te3 standard. Crystal structure has been determined by x-ray diffraction using Weissenburg and oscillation photographs, confirming that the layers have a fcc crystal structure with a lattice parameter of 18.50 Å, in excellent agreement with the bulk value. Band-gap measurements have been performed on the layers by photoreflectance. We report a value for the α-In2Te3 band gap of 1.19 and 1.31 eV at 300 and 77 K, respectively. Molecular-beam-epitaxial growth of InSb and CdTe on epitaxial In2Te3 films for fabrication of InSb/In2Te3/InSb and InSb/In2Te3/CdTe multilayers has been studied. Auger depth profiling of the resulting layers shows severe intermixing into the In2Te3. These results are supported by thermodynamic considerations of the InSb-In2Te3 interface.