Rapid growth of high-performance Bi2Te3 thin films by laser annealing at room temperature

Abstract

Bismuth telluride, (Bi2Te3), is of great scientific and technical importance due to its excellent thermoelectric performance near room temperature. However, deposition of Bi2Te3 thin films suffers from composition deviation due to preferential loss of Te at a high-temperature deposition environment. We demonstrated a fast and efficient laser annealing method to synthesize high-quality stoichiometric Bi2Te3 thin films at room temperature from Te/Bi stacking films. The production rate of Bi2Te3 was around 180 times higher than conventional thermal annealing. The formation of Bi2Te3 thin films was studied with respect to annealing laser energy density. Bi2Te3 thin films with an Bi:Te atomic ratio of 2:3 were achieved at an annealing laser energy density of 6.6 mJ/cm2. The structural, chemical, and thermoelectric performance of laser-annealed films were compared with conventional thermally annealed films. The Seebeck coefficient of laser-annealed films reached −167 µV/K, which was1.3 higher than that of thermally annealed films, evidencing the superiority of the laser annealing method in producing high quality Bi2Te3 stochiometric films. Rapid growth of stoichiometric Bi2Te3 thin films by laser annealing holds great promise for the development of high-performance thermoelectric devices.