Degradations of Optically-Pumped GaAlAs Double Heterostructures at Elevated Temperatures

We have measured the growth of dark line defects (DLD's) under optical pumping and the gradual decrease in photoluminescence (PL) intensity of the active layer in GaAlAs double-heterostructure wafers at elevated temperatures. Two different velocities of <100> DLD's are found which are considered to be dominated by α and β dislocations. A time lag is observed at the start of expansion of the <100> DLD's. The activation energies of the velocity and the time lag are found to be 0.2 eV and 0.3 eV repectively. The velocity increases and the time lag decreases with increase in Δ X . The gradual degradation rate of the PL intensity of the active layer in optically-pumped samples is ten to a hundred times as large as that without optical pumping. The activation energy is calculated to be 0.6 eV for the former degradation rate and 0.8 eV for the latter degradation rate.