Structural and electrical properties of epitaxial Bi2Se3 thin films grown by hybrid physical-chemical vapor deposition

We report the epitaxial growth of Bi2Se3 thin films on (0001) Al2O3 substrates by hybrid physical-chemical vapor deposition (HPCVD). The HPCVD technique combines the thermal decomposition of trimethylbismuth with the thermal evaporation of Se and leads to a high Se partial pressure in the growth ambient. The Bi2Se3 films are highly c-axis oriented on sapphire but contain planar defects including stacking faults and twin boundaries. Variable-temperature Hall-effect measurements demonstrate a carrier concentration of 5.8 × 10¹⁸cm^-3 and a mobility of 900 cm²/Vs at 4.2 K. These results demonstrate the potential of HPCVD for producing high quality Bi2Se3 films for topological insulator studies.