Thermoelectric properties of Bi₂Te₃ based thin films fabricated by pulsed laser deposition

Bi₂Te₃-based thin films were fabricated on glass substrates by the pulsed laser deposition (PLD) method. The vapor pressures of Bi and Te are significantly different, so controlling the stoichiometric composition is difficult when using conventional physical vapor deposition techniques, and the thermoelectric properties of Bi₂Te₃ films are sensitive to the film composition. PLD is a promising technique for the fabrication of telluride-based films such as Bi₂Te₃ due to its superior capability for controlling the film composition. Another advantage of PLD is the flexibility that it allows in terms of atmosphere in the reaction chamber; high concentrations of gases such as oxygen or argon can be introduced. We have measured various compositions of Bi₂Te ₃-based films, and have identified the optimal compositions for both n-type and p-type material. The thermal conductivities of these Bi ₂Te₃ films were evaluated by an exact measuring system, and the results were twice as low as those of conventional bulk materials. These results suggest that PLD has significant advantages for the deposition of in-plane Bi₂Te₃-based thin films.