The temperature dependence of 1.3- and 1.5-/spl mu/m compressively strained InGaAs(P) MQW semiconductor lasers

We have studied experimentally and theoretically the spontaneous emission from 1.3- and 1.5-/spl mu/m compressively strained InGaAsP 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/sub Rad/ is always well behaved and has a characteristic temperature T/sub 0/ (I/sub Rad/)/spl ap/T, as predicted by simple theory. This implies that the carrier density at threshold is also proportional to temperature. Below a breakpoint temperature T/sub B/, we find I /spl alpha/ n/sup Z/, where Z=2. And the total current at threshold I/sub th/ also has a characteristic temperature T/sub 0/ (I/sub th/)/spl ap/T, showing that the current is dominated by radiative transitions right up to threshold. Above T/sub B/, Z increases steadily to Z/spl ap/3 and T/sub 0/ (I/sub th/) decreases to a value less than T/3. This behavior is explained in terms of the onset of Auger recombination above T/sub B/; a conclusion supported by measurements of the pressure dependence of I/sub th/. From our results, we estimate that, at 300 K, Auger recombination accounts for 50% of I/sub th/ in the 1.3-/spl mu/m laser and 80% of I/sub th/ in the 1.5-/spl 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/sub 0/ (I/sub th/) above room temperature.