Power Dependence of the Recombination Processes in the In_xGa_1-xAs/GaAs Single Quantum Well

We have measured the power dependence of the photoluminesence spectra from a set of strained In_xGa_1-xAs/GaAs single quantum wells. The result shows that the excitation power has important effect on the carrier recombination processes. When the power increases from 0.5 to 14mW, the photoluminescence from the barrier becomes more intense than that from the well and the trapping efficiency decreases. At high excitation level, the ratio of the radiative recombination rate to the nonradiative recombination rate of the barrier increases ten times than that at lower excitation level, while it only doubles for the well.