Calculation of Auger rates in a quantum well structure and its application to InGaAsP quantum well lasers

We discuss the possible intrinsic limitation on the temperature dependence of threshold current of long wavelength InGaAsP quantum well lasers caused by Auger recombination and intervalence band absorption. A model calculation of the various band-to-band Auger rates are presented. We find that the Auger rates increase with decreasing band gap and also with increasing temperature as in the case of bulk semiconductors. The temperature dependence and the band-gap dependence arises from the energy and momentum conservation (in the direction normal to the well) that the four particle states involved must satisfy. The estimated Auger coefficient is large enough to be important in single quantum well lasers. However, the Auger effect should be much smaller in a multiquantum well laser than for a single quantum well laser. This is because the carrier density at threshold is smaller (by a factor of 3 to 4) for multiquantum well lasers than for single quantum well lasers. The increased intervalence band absorption with increasing temperature in the active layer may not be responsible for increased threshold current of single quantum well lasers.