Boron nitride films with different cubic phase contents were deposited in a radio frequency bias sputtering system by a two-stage deposition process. The Fourier transform infrared spectra and UV-visible transmittance and reflection spectra were measured. The optical absorption edge of BN films consists of a low energy region in which a increases exponentially as incident photon energy hn, and a high energy region, in which a varies as (hn)m, which is the characteristics of amorphous materials. These two regions are fitted by the Urbach tail model and the band-to-band transition model with an effective medium approach, and the Urbach energy and the optical band gap are determined from these fits. With an increase in the cubic boron nitride (c-BN) content, the absorption edge shifts to the higher energy and the optical band gap increases. For a BN film with 88% cubic phase, the optical band gap exceeds 6.0 eV, which is comparable to that of c-BN single crystal.

The well-crystallized cubic boron nitride (c-BN) films have been prepared on polycrystalline Ni substrates using a hot filament assisted rf plasma chemical vapor deposition method. X-ray diffraction showed that high quality c-BN lilms had been deposited without hexagonal BN (h-BN) or amorphous BN codeposition. Both (111) and (100) faces were observed in scanning electron microscopy images. These results suggested that Ni had catalyst effects on the nucleation and the growth of c-BN phase and inhibited the formation of h-BN.

Textured cubic boron nitride (c-BN) films have been deposited on (220) oriented crystallized polycrystalline nickel substrate by a hot filament assisted rf plasma chemical vapor deposition method. X-ray diffraction shows that the films are (220) preferentially grown, the peak ratio of (220) to the main peak [i.e., the (111) peak] is about 5.2. The scanning electron microscopy images exhibit regular grain shapes. Most of the grains are rectangular, also indicating the (220) growth. The grain size is about 5mm. The well-matched Ni lattice with c-BN, the catalytic effect of Ni, and the appropriate rf bias are considered to be the key factors in the textured growth.

In order to investigate the growth mechanism of diamond thin films, the in situ optical emission spectra of direct current (dc) arc discharge plasma, including the spatial distributions and different CH4/H2 ratios, have been measured during the growth processes of diamond thin films prepared by the dc arc discharge plasma chemical vapor deposition method. The results show that there are a great number of atomic hydrogens in the arc discharge piasma. This is the key factor for the growth of diamond films with a high rate and high quality. In addition, the effects of the CH4/H2 ratio on the quality of diamond films are discussed in detail in this letter.