ELECTRONIC-PROPERTIES IN P-TYPE GAN STUDIED BY RAMAN-SCATTERING

Raman spectra from p-type GaN have been systematically studied in the hole density range of 5 X 10(16) -1 X 10(18) cm(-3). Contrary to the c ase of n-type samples, spectral profiles of the LO-phonon-plasmon coup led mode in p-type show no remarkable change with the hole density. Th us, precise evaluation of electrical transport parameters such as carr ier density and mobility from the coupled mode profile is difficult. H owever, a continuum band has been observed in the low-frequency range of the spectra, becoming intense with the increase of the hole density . This band has been attributed to the inter-valence-band transition o f holes, and the intensity can be used as a good measure of the hole d ensity. (C) 1998 American Institute of Physics. [S0003-6951(98)02540-6 ].