Cubic boron nitride (cBN) thin films have significant and potential technological application prospect in cutting tools, electronic and optical devices, etc., because cBN possesses excellent physical and chemical properties, such as ultrahigh hardness only inferior to diamond, inertness against oxidation at high temperature, uneasy reaction with iron group metal, as well as the possibility of using as n-and p-type doped semiconductors. The preparation and property research of cBN film have been one of difficult and attractive field in the scientific world. This dissertation focuses on the preparation of cBN films, their optical gaps, and the characteristics of BN(n-type)/Si(p-type) heterojunction. Boron nitride (BN) thin films were deposited on Si substrates using the conventional radio-frequency (RF) sputtering system, with hexagonal boron nitride (hBN) target and working gas of argon (or mixture of nitrogen and argon). The influence of various factors, such as substrate bias voltage and temperature, working gas pressure, types of Si wafer, etc. on the preparation of cBN has been studied systematically. The films were characterized by Fourier transform infrared spectrophotometer (FTIR). Moreover, the surface morphology of the films was observed by a Scanning electron microscope (SEM). The transmittance and reflectance spectra of BN films were obtained as a function of incident photon wavelengths, and the thickness of films was measured by Alpha-step meter. On the p-type Si wafer, the n-type BN film was prepared by implanting sulfur ions into it. I-V curves of BN(n-type)/Si(p-type) heterojunction were obtained by the low resistance meter. Based on analyzing the phases of BN film and the optimized deposition conditions, the cBN film with cubic phase content up to 95% was prepared. In order to improve the adherence of the film to the substrate and the repeatability of synthesis, we invent a three -step approach, which comprised the steps of turbostratic boron nitride (tBN) turning into rhombohedral boron nitride (rBN) as the first, rBN turning into cBN as the second and deposition as the last. Either the substrate temperature or the bias voltage as a parameter of particular interest was rised first and reduced after it. While working gas was switched from Ar in the first and second steps to Ar+N2 in the third one.