CRYSTAL-GROWTH OF BI2TE3 ON SINGLE-CRYSTAL SUBSTRATE SB2TE3 BY MOLECULAR-BEAM EPITAXY

We have grown stoichiometrically thin films of the narrow bandgap semiconductor Bi2Te3 by molecular beam epitaxy in an ultra-high vacuum on single-crystal substrate Sb2Te3 in order to optimize the growth conditions for this technique. High resolution X-ray diffraction, scanning electron microscope observations and energy dispersive X-ray spectroscopy analysis are used to ha characterize the substrate and the deposited layers. In addition, secondary ion mass spectroscopy depth profiling is used to study the diffusion and the concentration profiles of layer elements. We have also studied the effect of heat treatment on some of the electrical properties of single-crystal substrate as a function of temperature in order to analyse its semiconducting behaviour at low temperature. The sticking coefficients K(s)(Te) and K(s)(Bi) of the elements Te and Bi, respectively, are determined as a function of substrate temperature T(S) and flux ratio F(R) = [F(Te)/F(Bi)]. It is found that K(S)(Te) is very sensitive to both T(S) and F(R) changes, it them acts as a basic element in the determination of the range of T(S) and F(R) in which the deposited layer is grown stoichiometrically.