Pulsed laser deposition of skutterudite thin films

Skutterudite (CoSb3 and IrSb3) thin films of high phase purity and crystallinity have been prepared by pulsed laser deposition. It is found that while the crystallinity of the films increases with increasing temperature, the phase purity decreases due to antimony volatility. The skutterudite phase can be stabilized to higher temperature by addition of excess antimony to the pulsed laser deposition target. Target-to-substrate distance must be optimized to obtain stoichiometric skutterudite films with low stress. A decrease in the flux of energetic particles and changes in particle stoichiometry with increasing distance caused by plume tilting results in lower film stress, but the diantimonide phase is nucleated if the distance is too large. It is possible to further reduce compressive stress by growing films in an inert background gas to decrease the flux of energetic particles. Overall, the highest quality films are grown from targets with excess antimony at a temperature of 270 degreesC with a target-to-substrate distance of 7 cm and a background argon gas pressure of 10 mTorr. The resistivity, mobility, and carrier concentration of these films are indicative of a degenerate p-type semiconductor with hole concentrations in the range of previously measured bulk values. (C) 2001 American Institute of Physics.