氮化銦之拉曼光譜分析

Abstract

In this thesis, we study InN epifilms using both conventional and cross-sectional Raman spectroscopy. Firstly, we found that the variation of the plasmon-longitudinal phonon coupling with carrier concentration agrees with what was previously reported. In addition, we also found direct evidence for the existence of residual strain along the growth direction of the InN films. This result is very useful for the understanding of the depth dependence of the physical properties. We also showed that cross-sectional Raman spectroscopy can be used to study certain vibration modes that are normally not observable in the normal surface Raman configuration. On top of that, the A1(TO) mode was found to become increasingly prominent on approaching the interface between the InN and the GaN buffer layer, a fact we attributed to the high density of dislocations near the interface. Lastly, our study has shed more light on the mechanism for the formation of the A1(LO) mode in the Raman spectrum of InN.