Threshold‐temperature characteristics in (GaAl)As visible laser diodes emitting below 750 nm

The temperature dependence of the threshold current Ith has been measured for (GaAl)As v‐channeled substrate inner stripe lasers emitting in the wavelength range of 781–697 nm. Ith (350 K)/Ith (300 K) is found to increase below 750 nm with decreasing wavelength in spite of the fairly large heterojunction step height Δx of 0.4. This is well explained by the model of carrier leakage due to unconfined carriers in the active layer. The calculation indicates that the threshold‐temperature sensitivity below 750 nm is almost determined by the carrier leakage in the cladding layer when Δx is smaller than ∼0.4, and it is determined by the temperature dependence of the fraction of the total electrons in the direct conduction band of the active layer when Δx is larger than ∼0.6.