Nanostructured Sb2Te3 films composited with Bi2S3 for p–n conduction type conversion

Abstract

The crystallization of p-type Sb2Te3 material can be tuned deterministically through compositing with n-type Bi2S3. The underlying changes in conduction from p-type to n-type are due to the crystallization changes induced by the composited Bi2S3 and the simultaneous changes in crystalline phase type. Bi2S3 nanoprecipitate formation and crystallization transition could effectively stimulate the p–n conduction transition. Upon annealing, pure Sb2Te3 partially crystallizes from the as-deposited state, which exhibits continuous crystallization during annealing. The formation of the p-type Sb2Te3 phase and the Sb2O3 phase in pure Sb2Te3 films through oxidation is significantly suppressed through compositing with excess Bi2S3. Moreover, the crystallization temperatures of the Sb2Te3–Bi2S3 films exceed 200 ℃, and the Seebeck coefficients and carrier concentrations of the samples are larger than those of pure Sb2Te3. The X-ray diffraction and Raman spectroscopy characterization of the crystalline thin films reveals a local change of the bonding arrangement around Sb atoms during crystallization. Our results suggest that Sb2Te3–Bi2S3 can serve as a promising candidate for thermoelectric applications based on n-type conduction.