The effects of substrate bias and Si doping on the properties of rf sputtered BN films

This paper reports that the effect of substrate bias on the properties of rf sputtered boron nitride films on Si and GaAs substrate were investigated. IR transmission and reflectivity of films with different substrate bias were measured with Perkin Elmer 983 IR spectroscopy. From the IR reflectivity data, transverse optical mode (TO) and longitudinal optical mode (LO) frequencies were derived by fitting Kramer-Kronig model. Absorption coefficient was determined from IR transmission data. The resultant TO and LO modes showed that substrate bias caused broadening of reststrahlen band of rf sputtered boron nitride. We also tried to dope boron nitride films with silicon by alternate sputtering of BN and Si targets controlling sputtering time of each target followed by annealing. Electrical resistivity was measured over the temperature range between 175 K to 370 K for both intrinsic and Si-doped boron nitride films. Intrinsic rf sputtered boron nitride showed little change in resistivity (109 Ω cm - 1011 Ω cm) over the temperature range studied