Optical study of AlGaN/GaN multiple quantum well structures grown on laterally overgrown GaN templates

We report on optical studies of Al0.1Ga0.9N/GaN structures with five 30 (A) over circle thick GaN quantum wells (QWs) grown by metal organic vapor phase epitaxy using the lateral overgrowth technique. Overgrown regions demonstrate better structural and optical properties. The low temperature photoluminescence (PL) is dominated by the multiple quantum well (MQW) emission at 3.53 eV with the linewidth of similar to50 meV. The PL decay time for this line was measured to be similar to600 ps. Comparison with an AlGaN/GaN MQW light-emitting diode (LED) structure is done. The LED structure was grown with a p-type doped AlGaN top layer and a p-GaN contact layer. The PL spectrum of the LED structure shows besides the donor-acceptor pair recombination from the top layer an additional 60 meV wide line at 3.64 eV. The presence of two MQW peaks may be related to the potential gradient present across the MOW structure.