Temperature dependence of the Raman-active modes in the semipolar (11 2¯2) plane GaN Film

Temperature dependences of the polarized Raman scattering spectra in the backscattering configuration of the semipolar (11 2¯2) plane GaN thin film are analyzed in the range from 83 K to 563 K. The semipolar GaN film is cut at a tilted angle from polar GaN wafer grown by hydride vapor phase epitaxy. The spectral features of the frequency shift and linewidths of the Raman-active phonon modes Quasi-TO, E1 (TO), E2 (high), and Quasi-LO are prominently revealed, and the temperature coefficients corresponding to the lattice thermal expansion and phonon anharmonic effect, as well as defects and impurities in crystals, are well deduced by the theoretical equations. With the increasing temperature, the Raman scattering peaks would substantially shift to lower frequencies and the linewidths gradually broaden. Our studies will lead to a better understanding of the fundamental physical characteristics of the semipolar (11 2¯2) plane GaN film.