Crystal growth of Bi2Te3on single-crystal substrate Sb2Te3by molecular beam epitaxy†

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Abstract
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 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 Ks(Te) and Ks(Bi) of the elements Te and Bi, respectively, are determined as a function of substrate temperature Ts and flux ratio FR = [F(Te)/F(Bi)]. It is found that Ks(Te) is very sensitive to both Ts and FR changes, it them acts as a basic element in the determination of the range of Ts and FR in which the deposited layer is grown stoichiometrically.