Room-temperature fast deposition and characterization of nanocrystalline Bi0.4Sb1.6Te3 thick films by aerosol deposition

P-type nanocrystalline Bi0.4Sb1.6Te3 thick films were directly deposited on copper substrates by aerosol deposition (AD) involving shock compaction of the starting powder at room temperature. The film deposition rate was over 700 mu m/min. The relative density of the films was above 95%. Films with a thickness of over 2 mm were obtained. They consisted of nanocrystals with grain sizes of several tens of nanometers. The crystal structure of the films was the same as the bulk materials prepared by spark plasma sintering (SPS) using the same starting powder. We measured the electrical conductivity, carrier concentration, Hall mobility, and thermal conductivity of the films and compared them with those of the bulk materials. The thermal conductivity of the AD film was 20-30% lower than that of the bulk materials, which is attributed to the increased number of grain boundaries and some defects in the AD films.