Strain and microstructure in Fe-doped GaN layers grown by low pressure metalorganic vapour phase epitaxy

Abstract

In order to get semi-insulating GaN layers with a low dislocation density on sapphire, two kinds of Fe doping were explored by low pressure metalorganic vapour phase epitaxy (LP-MOVPE): the modulation doping (MD) and the continuous doping (CD). The high crystalline quality and the semi-insulating character are obtained in the case of the Fe-MD layers. The effect of Fe doping on the strain was investigated in both kind of layers (MD and CD) by X-ray diffraction, photoluminescence and reflectivity. The lattice parameters are functions of the iron doping level, whatever the doping mode.