Self-Assembled InP/GaInP Quantum Dot Lasers

AbstractSelf-assembled quantum dots of InP in In0.48Ga0.52P can be formed by molecular beam epitaxy (MBE) due to the strong lattice mismatch of 3.7 %. This is a promising method to realize small quantum dots which exhibit strong quantization effects and represent real 0D systems. Lasers with quantum dots in the active region should exhibit very low thresholds due to the low discrete density of states in quantum dots. On the other hand the self organized dots exhibit a considerable size fluctuation leading to an inhomogeneous broadening of the gain spectrum. We have measured the optical gain in quantum dots at room temperature and found two gain peaks which are identified as being due to the wetting layer and the quantum dots by their polarization properties. As expected from the results of the gain measuremlents, cleaved samples under optical pumping show lasing at room temperature of either the quantum dots or of the wetting layer, depending on the experimental conditions.