PHASE EVOLUTION IN BORON-NITRIDE THIN-FILMS PREPARED BY A DC-GASDISCHARGE ASSISTED PULSED-LASER DEPOSITION

Boron nitride (BN) thin films were deposited on a Si(lll) substrate us ing ArF pulsed excimer laser radiation for ablating a hexagonal BN (hB N) target and a dc-gasdischarge for activating N-2. The present phases in the films were determined by Fourier transformation infrared spect roscopy (FTIR). The results show that BN thin films containing largely cubic BN (cBN) phase on Si(lll) substrates were successfully prepared by this dc-gasdischarge assisted pulsed laser deposition (PLD). The e ffects of the dc-gasdischarge and the chamber background gas on the fo rmation of the cBN thin films were analyzed. The reasons for the phase evolution from hBN to cBN induced by the dc-gasdischarge are discusse d. The results suggested that the dc-gasdischarge has two effects on t he formation of cBN thin films. On one hand, it activated N-2 and caus ed the formation of nearly stoichiometric BN films. On the other hand, it caused the activated ions to bombard the substrate and induced the formation of the cBN phase. The dual beam ion source assisted PLD met hod is proposed to be the most promising method in preparing cBN films .