Thermoelectric Properties of Boron and Boron Phosphide Films

Abstract

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 high-temperature 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.