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

Abstract

We have studied experimentally and theoretically the spontaneous emission from 1.3- and 1.5-μm compressively strained InGaAs(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 IRad is always well behaved and has a characteristic temperature T0 (IRad) ≈ T, as predicted by simple theory. This implies that the carrier density at threshold is also proportional to temperature. Below a breakpoint temperature TB, we find I ∞ nZ, where Z = 2, and the total current at threshold Ith also has a characteristic temperature T0(Ith) ≈ T, showing that the current is dominated by radiative transitions right up to threshold. Above TB,Z increases steadily to Z ≈ 3 and T0 (Ith) decreases to a value less than T/3. This behavior is explained in terms of the onset of Auger recombination above TB, a conclusion supported by measurements of the pressure dependence of Ith. From our results, we estimate that, at 300 K, Auger recombination accounts for 50% of Ith in the 1.3-μm laser and 80% of Ith in the 1.5-μm 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 To(Ith) above room temperature.