Synthesis of cubic boron nitride thin films by ion-assisted pulsed laser deposition

Abstract

Boron nitride films have been deposited on Si (100) substrates by ion-assisted pulsed laser deposition. In this arrangement, ahexagonal boron nitride (hBN) target is ablated by an excimer laser to supply energetic boron and nitrogen species, while broadly- focussed ion bombardment with Ar and N2 is used to enhance the growth of the cubic phase and to modify chemical stoichiometry. The dependence of the cubic-to-hexagonal phase ratio on deposition parameters such as substrate temperature, laser fluence and ion flux and energy are extensively studied; in particular, the effects of growing the cubic boron nitride (cBN) structure at different laser wavelengths (308 and 248 nm) are discussed. The deposited films are characterized by Fourier transform infrared spectroscopy, Auger electron spectroscopy and electron-energy-loss spectroscopy. These results indicate that the cubic phase is unlikely to be formed at room temperature or without ion irradiation.