Effects of strain and Mg-dopant on the photoluminescencespectra in p-type GaN

Abstract

The photoluminescence (PL) spectra of Mg-doped GaN on sapphire have been measured at 12K. The residual strain induced by the mismatch of the lattice constants and thermal expansion between GaN epilayers and substrates have been investigated by micro-Raman scattering and x-ray diffraction. Redshifts of the ultraviolet PL bands were observed in Mg-doped GaN after annealing in nitrogen ambient, which may be related to the carrier concentration and the strain in the epilayers. For heavily Mg-doped GaN films, the hole concentration in GaN, which shifts the PL peaks, is the dominant influence, whereas the strain is comparatively secondary.

Effects of annealing temperature on amorphous GaN films formed on Si(1 1 1) by pulsed laser deposition

“…So far, all the Raman active modes belonging to the C 6V symmetry group have been detected. In the case of hexagonal wurtzite with the c-axis perpendicular to the surface, the TO branches of the A 1 mode both the TO and LO branches of the E 1 mode are forbidden in the backscattering configuration [17]. Only the LO branches of the A 1 mode and the E 2 mode are allowed to appear in the Raman spectra.…”