Thermoelectric Properties of Boron and Boron Phosphide Films

Amorphous boron and boron phosphide films were prepared on silica glass by a solid source molecular beam deposition (SSMBD) method and a low-pressure chemical vapor deposition method (LPCVD) by adapting gas source molecular beam deposition at a reactant pressure of 1.33 Pa. The films were characterized by X-ray diffraction, X-ray photon electron spectroscopy (XPS), and Hall effect measurements. The experimental results on film growth were correlated with the calculation by an ab initio molecular orbital method. The hightemperature electrical conductivity and thermoelectric power of these films were measured to evaluate the thermoelectric figure-of-merit (Z), which was determined by the electrical conductivity of the films. In particular, the Z value for SSMBD boron and LPCVD boron phosphide films was higher (10-5/K) than those of LPCVD boron films, indicating that they are promising high-temperature thermoelectric materials