Optical gain in InGaNInGaAlN quantum well structures with zero internal field

Electronic and optical properties of InGaNInAlGaN quantum well with zero internal field were investigated by using the non-Markovian gain model with many-body effects. The In composition x in the well to give zero internal field is shown to increase with the In composition y in the barrier. The InGaNAlGaInN system has much larger optical gain than the conventional InGaNGaN system because the optical matrix element is largely enhanced due to disappearance of the internal field. The peak gain is shown to decrease with increasing In composition for both systems. The decrease in the optical gain for the InGaNAlGaInN system is mainly due to the reduction in quasi-Fermi-level separation while that for the InGaNGaN system is due to the reduction in the matrix element.