Light emission enhancement in blue InGaAIN/lnGaN quantum well structures

摘要

Optical properties of blue AlInGaN/InGaN quantum well (QW) structures with a quaternary AlInGaN well layer were investigated by using the non-Markovian gain model with many-body effects. The band-gap expression of the AlInGaN materials was determined through a comparison with experimental results. We found that the emission peak can be enhanced by using quaternary AlInGaN well and is sensitive on In composition in the InGaN barrier. For example, the spontaneous emission coefficient for Al_(0.08)In_(0.22)Ga_(0.67)N/InxGa_(1-x)N QW structures shows a maximum at In composition of 0.13 in the barrier and gradually dacreases with increasing In composition. This is attributed to the fact that the quasi-Fermi-level separation linearly decreases with increasing In composition in the barrier due to the decrease in the conduction and valence band offsets. The AlInGaN/InGaN system with zero internal field is found to have smaller emission peak than the AlInGaN/InGaN system with nonzero internal field due to smaller band offsets.