Gain-current characteristics of strained AlGaInP quantum well lasers

Single quantum well AlGaInP lasers, each having a 65 Å width well have been fabricated with GaxIn1−xP well compositions from x=0.43 to 0.54 grown on substrates orientated 10° off the (100) axis. The threshold currents have been measured from 120 K to room temperature and the samples show a systematic variation with x. At low temperature the results are in good agreement with our calculated gain-current curves and we show that at room temperature the rapid increase in threshold current density with decreasing length is due to a thermally activated leakage current rather than gain saturation.