Influence of GaN barrier growth temperature on the photoluminescence of InGaN/GaN heterostructures

We report a study of the emission properties of InGaN/GaN quantum wells, grown by metalorganic vapour phase epitaxy, as a function of barrier-growth temperature, using continuous wave and time-resolved photoluminescence spectroscopy. We observe that high barrier-growth temperatures lead to a blue-shift of the photoluminescence, a reduction of the recombination lifetime, and a broadening of the emission linewidth. These effects are consistent with increased indium desorption during the pause preceding the growth of the barrier at higher temperatures. The blue-shift and the reduced lifetime are consistent with a reduction of the average indium concentration, while the increase of the linewidth is caused by the increase of the indium composition fluctuations due to the randomness of the desorption process. At the same time, the high barrier temperature samples have the highest photoluminescence efficiency at room temperature due to the reduced number of defects in the barrier.