Micro-Raman characterization of InGaN/GaN single quantum well nanocolumns on Si(111) substrate

The phonon mode behavior of InGaN/GaN single quantum well (SQW) nanocolumns grown on silicon (111) substrate was investigated by micro-Raman scattering technique. The samples were synthesized using radio frequency (RF) plasma-assisted molecular beam epitaxy (MBE). High temperature (1020°C) grown AlN (about 5 nm) was used as a buffer. Raman spectra were recorded at room temperature with a confocal micro-Raman spectrometer in the backscattering geometry. The Raman spectra showed that the \( E_2^{\mathrm{high}} \) mode of GaN and the AO phonon mode of silicon were clearly visible. On the basis of these studies, the tensile stress and size of the GaN nanocolumns were calculated with respect to the \( E_2^{\mathrm{high}} \) mode of GaN. The nanosize dependence of the peak shift of the \( E_2^{\mathrm{high}} \) mode was discussed. These results were in good agreement with the calculated spatial correlation model.