Rapid thermal annealing has been shown to enhance the photoluminescence efficiency as well as laser performance in InGaAs/GaAs, and AlInGaAs/AlGaAs quantum well lasers. The annealing also is known to cause interdiffusion of Ga and In atoms, yielding a graded InGaAs/GaAs interface. One of the advantages of a graded interface is the gradual transition of strain at the interface. Unfortunately, the interdiffusion due to annealing is not entirely predictable or repeatable and the effect on photoluminescence efficiency is not well understood.