Hybrid physical–chemical vapor deposition of Bi₂Se₃ films

Bi₂Se₃ thin films were grown on c-plane sapphire substrates by hybrid physical-chemical vapor deposition (HPCVD) using trimethyl bismuth (TMBi) and Se pellets. A Se-rich environment is created by evaporating Se pellets in the vicinity of the substrate, which is used to suppress the formation of Se vacancies. The effects of pre-cracking temperature and substrate/Se temperature on the growth rate, structural and electrical properties of the Bi₂Se₃ films were investigated. C-axis oriented films were obtained which show a reduction in the carrier concentration as pre-cracking temperature was increased from 290 °C (1.6×10¹⁹ cm⁻³) to 350 °C (8.4×10¹⁸ cm⁻³). An additional reduction in carrier concentration (7.28×10¹⁸ cm⁻³) was observed on increasing the substrate temperature from 200 to 260 °C.