Temperature dependence of threshold current in (GaAl)as double-heterostructure lasers with emission wavelengths of 0.74-0.9µm

The threshold-current variation with temperature has been measured for Ga1-xAlxAs double-heterostructure (DH) lasers with AlAs mole fraction in the active layer of 0.08 and 0.2, and with several heterojunction step heights . The threshold-temperature coefficient Jth(350 K)/Jth(300 K), which generally increases with decreasing , is found to be larger for than that for at the same value of , and also to be larger for the lasers with smaller effective electron diffusion length in the cladding layer, in the case of . These characteristics are well explained by a model of carrier leakage due to unconfined carriers in the active layer. It is confirmed by a good fit of the experimental results with the calculated values that the electron leakage in the conduction band of the cladding layer dominates for , but the hole leakage in the cladding layer increases with and becomes comparable in magnitude with the electron leakage at .