Influence of substrate misorientation on quality of active region and performance of [formula omitted] triple-quantum-well lasers grown by molecular beam epitaxy

Abstract

The influence of substrate misorientation on the quality of the active region with low AlAs portion barrier layers and the performance of the GaAs AlGaAs grade index separate-confinement triple-quantum-well lasers grown under at a higher CO pressure are investigated. It is found that the threshold current could be reduced from 32.5 to 15.7 mA by tilting the substrate 6° and the high-quality lasers show a characteristic temperature as high as 260°C, indicating a high output stability. The luminescence results reveal that carbon impurity, like oxygen, could also be incorporated and trapped at and near AlGaAs GaAs interfaces during growth and cause roughness, resulting in excessive scattering and loss and thus a high threshold current. Substrate misorientation for 6° toward 〈1 1 1〉A could reduce the incorporation of carbon impurity to an unobservable level.