Scanning Electron-Microscopy Investigations Of The Initial Degradation Mechanism Of Gaas Quantum-Well Lasers Grown On Silicon Substrates

Cathodoluminescence and electron beam induced current are used to investigate the degradation of the graded-index separate-confining heterostructure laser devices grown on silicon substrates. By examining the evolution of the microscopic electronic properties of these devices during operation or under electron beam bombardment, a better understanding of the initial mechanism of degradation in a laser device results: it is concluded from this study that the degradation starts in the vicinity of the p-n junction before attaining the active layer or the formation of dark line defects. This starting of degradation is attributed to the point-defect migration or coupling in the space-charge region. The built-in electrical field plus the nonradiative recombination of excesses carriers seems to be related to these phenomena. It is also pointed out that the technological processes for device fabrication have a strong influence on the degradation mechanism.