Stacking Fault Emission In Gan: Influence Of N-Type Doping

We present spatially and spectrally resolved cathodoluminescence investigations on the cross section of semipolar (11 (2) over bar2) gallium nitride epitaxial layers with high background doping level. The locally varying high carrier concentration leads in emission to a free electron recombination band (FERB) governed on the high energy side by conduction band filling. For the basal plane stacking fault (BSF) of type I-1, typically emitting at approximate to 3.41 eV in low doped GaN, we find a blue shift in emission correlated to the FERB high energy tail. This shift can be perfectly modeled and understood in a quantum well model for the BSF, taking also into account the varying doping level in the barrier region. Thus, the carrier concentration can be finally calculated either from the actual position of the I1 BSF or alternatively from the FERB-related near band edge emission. Published by AIP Publishing.