Deep-level changes in (Al,Ga)As double-heterostructure lasers degraded during accelerated aging at high temperatures

Deep levels in (Al,Ga)As double-heterostructure lasers have been studied by deep-level transient spectroscopy during accelerated aging at junction temperatures in the 120–320 °C range. A marked correlation has been found between the concentration increase of a hole trap and the threshold increase in degraded lasers. This hole trap is at 0.24 eV from the valence band in the n-AlGaAs passive layer. Capture cross section of this level at 145 K was 2×10−19 cm2 for electron capture and ≳5×10−15 cm2 for hole capture. The 0.24-eV-trap increasing rate was accelerated with an activation energy of 0.54±0.07 eV as the aging temperature was raised. The 0.24-eV trap seems to be closely related to the ’’slow long-term degradation’’ in (Al,Ga)As lasers and LED’s, which limits the lifetime of these devices to 105–106 h at room temperature.