RAMAN ACTIVE E_2 MODES IN ALUMINIUM NITRIDE FILMS

摘要

The vibrational spectrum of AlN thin films have been studied in the last years by few researchers and little attention has been paid to their two Raman active E_2 modes. This work was performed to clarify some disagreements that have been appeared in the literature on analysis of these two Raman modes of AlN. Carlone et al~1 have indicated that the E_2 modes of AlN deposited on Si occur at frequencies 303 and 426 cm~(-1). In the present work, Raman spectra of AlN deposited on polished Si, quartz and BK7 substrates and also Raman spectrum of pure Si, were compared to show that the peaks at 303cm~(-1) and 426cm~(-1) can actually be assigned as Raman peaks of Si, instead of AlN. In summary this work brings out new light to elucidate the analysis of Raman spectra of AlN films deposited on silicon. We show that the Raman lines at 240 cm~(-1) and 650 cm~(-1) are the real AlN peaks in agreement with calculated and experimental works reported in the literature that indicate the occurrence of AlN Raman lines in the ranges of (228-252) cm~(-1) and (631-665) cm~(-1).