CARRIER SPILLOVER AT 300, 195, AND 77 K IN INGAAS AND GAAS SINGLE QUANTUM-WELLS

The carrier recombination rates in GaAs and strained InGaAs-GaAs singl e-quantum-well lasers of varying well width and potential depth, respe ctively, have been measured at 300, 195, and 77 K. For the InGaAs quan tum wells (QWs), the carrier lifetime saturates at high inversion, wit h both the Shockley-Read (SR) lifetime and the saturation lifetime sho wing substantial reductions with decreasing temperature. The large red uction in the SR lifetime may be attributed to the increased effective ness of acceptor ions as trap sites, due to the reduced carrier moment um at lower temperature. In a similar vein, the saturation lifetime is also reduced, due to the enhanced carrier confinement in the QW, brou ght about by the decrease in the carrier thermalization. For the GaAs QWs at 300 K, the saturation lifetime decreases as the well width is i ncreased. The recombination rate law of bulk material is inadequate to predict the recombination rates in these QWs. Consequently, a local r ecombination model has been developed which accurately predicts the ob served lifetime saturation behavior as a function of well width, poten tial depth, and temperature. Further, T-0 of 95 and 162 K are calculat ed for the shallow and deep QW lasers, respectively. This calculation suggests that it is the temperature dependence of the differential gai n that is the dominant factor in setting the temperature sensitivity o f the InGaAs QW lasers.