Characterization of (Bi_0.25Sb_0.75)₂Te₃ Deposited by Pulsed Laser Deposition

The main objective of this work is to investigate the possibility of preparing bismuth telluride thin films using pulsed laser deposition. The effect of varying the deposition pressure, laser fluence, and the deposition temperature on the surface roughness, film composition, grain microstructure and electrical resistivity is analyzed using, scanning electron microscopy, atomic force microscopy, X-ray fluorescence, transmission electron microscopy, and four point probe measurements. It is demonstrated that relatively smooth films can be deposited at a laser flounce of 0.6 J/cm² and using argon as a background gas at 10⁻¹ mbar. On the other hand, resistivities as low as 2 mΩ.cm can be obtained by either depositing the film at 200°C, or by post-laser annealing films deposited at room temperature.