Abstract
The effect of growth conditions on the Al composition and optical properties of AlxGa1−xN layers grown by atmospheric-pressure metal organic vapor phase epitaxy is investigated. The Al content of the samples is varied between 3.0% and 9.3% by changing the gas flow rate of either trimethylaluminum (TMA) or trimethylgallium (TMG) while other growth parameters are kept constant. The optical properties of the AlxGa1−xN layers are studied by photoreflectance and time-resolved photoluminescence (TR-PL) spectroscopies. A degeneration in the material quality of the samples is revealed when the Al content is increased by increasing the TMA flow rate. When the TMG flow rate is decreased with a fixed TMA flow rate, the Al content of the AlxGa1−xN layers is increased and, furthermore, an improvement in the optical properties corresponding with an increase in the PL decay time is observed.
•AlxGa1−xN layers grown by atmospheric-pressure metal organic vapor phase epitaxy•Al content is varied by changing the trimethylaluminum (TMA) or trimethylgallium (TMG) flow rate•Al content increased by increasing (reducing) the TMA (TMG) flow rates.•Degeneration (improvement) in optical properties by increasing (reducing) the TMA (TMG) flow rates•Unexpected increase in the PL decay time is observed with decreasing TMG flow rates.