OPTICAL-PROPERTIES OF CUBIC BORON-NITRIDE

Optical properties of cubic boron nitride were studied in the spectral range from 400 to 50 000 cm(-1) Raman-scattering, absorption, and ref lection spectra were measured. The regions of the one-phonon and multi phonon absorption were studied in detail and the energies of the phono ns were determined. The dispersion of the refractive index in the rang e 400-28 000 cm(-1) was obtained from measurements of interference spe ctra on plateletlike samples. A model including one-phonon and Sellmei er electron oscillators was used to fit the dispersion of the refracti ve index. Both the static and high-frequency dielectric constants epsi lon(0) and epsilon(infinity), were obtained and found to be 6.80 and 4 .46, respectively. The parameters of the phonon oscillators were used for simulation of the interference spectra in transmission and reflect ion. Techniques for preparing free-standing samples of dimensions of t he order of 150X150 mu m and of thickness down to 0.2 mu m are describ ed as well as methods to measure their thickness.