Performance improvement of electrodeposited Bi 2 Te 3 thin films using homogeneous electron beam irradiation and thermal annealing

We investigated the structual and thermoelectric properties of electrodeposited Bi 2 Te 3 thin films using a two-step process which combined an homogeneous electron beam irradiation with a thermal annealing. The Bi 2 Te 3 thin films were formed on stainless steel substrates by the potentiostatic electrodeposition. We first performed only the thermal annealing to the thin films to determine the optimal annealing temperarure. As a result, we found that the Bi 2 Te 3 thin films at the annealing temperautre of 300 °C exhibited the highest thermoelectric performance, which was 4.5 times higher than that of the as-deposited thin films. Thus, in the two-step process, the electron beam irradiation dose was changed from 0.36 to 1.08 MGy while the annealing temperature was set at 300°C. As a result, the Bi 2 Te 3 thin films at the EB irradiation dose of 0.36 MGy exhibited highest thermoelectric properties [power factor = 6.1 μW/(cm·K 2 )] which was approximately 20% higher than that of the optimized thin films with only the annealing treatment. Therefore, we conclude that two-step process is beneficial to improve the thermoelectric properties of electrodeposited Bi 2 Te 3 thin films.