The temperature dependence of 1.3-and 1.5-μm compressively strained InGaAs(P) MQW semiconductor lasers

We have studied experimentally and theoretically the spontaneous emission from 1,3- and 1.5-mu m compressively strained InCaAs(P) multiple-quantum-well lasers in the temperature range 90-400 K to determine the variation of carrier density n with current I up to threshold. We find that the current contributing to spontaneous emission at threshold I-Rad is always well behaved and has a characteristic temperature T-0 (I-Rad) approximate to T, as predicted by simple theory. This implies that the carrier density at threshold is also proportional to temperature. Below a breakpoint temperature T-B, we find I proportional to n(Z), where Z = 2, and the total current at threshold I-th also has a characteristic temperature T-0(I-th) approximate to T, showing that the current is dominated by radiative transitions right up to threshold, Above T-B, Z increases steadily to Z approximate to 3 and T-0 (I-th) decreases to a value less than T/3. This behavior is explained in terms of the onset of Auger recombination above T-B. a conclusion supported by measurements of the pressure dependence of I-th From our results, we estimate that, at 300 K, Auger recombination accounts for 50% of I-th in the 1.3-mu m laser and 80% of I-th, in the 1.5-mu m laser, Measurements of the spontaneous emission and differential efficiency indicate that a combination of increased optical losses and carrier overflow into the barrier and separate confinement heterostructure regions may further degrade T-0 (I-th) above room temperature.