Positive feedback model of defect formation in gradually degraded GaAlAs light emitting devices

Defects in gradually degraded GaAlAs (0.8 µm wavelength) light emitting diodes have been evaluated by transmission electron microscope (TEM) and deep-level transient spectroscopy (DLTS). Two stages increase of deep-level defects has been observed by DLTS during device operation (reported in a previous paper). On the other hand, very small dislocation loops (15-50 nm in diameter) were observed in the active region by TEM at the end of the device operation. The nature of the dislocation loops was determined to be interstitial Frank loops with Burgers vector of ( /3)