Effect of Fe doping on optical properties of freestanding semi-insulating HVPE GaN:Fe

Systematic study of optical properties of undoped and Fe-doped substrates grown by hydride vapor phase epitaxy has revealed a strong dependence of the photoluminescence, transmission, reflectivity and ellipsometric spectra on the Fe-doping level. The changes of the near-band-gap transmission, reflectivity and photoluminescence has been observed and ascribed to the absorption introduced by the density of states tails, and the Fe3+-ions incorporated in the GaN-lattice. Several approaches towards quantifying the Fe-doping level are suggested.