Electrical and optical properties of self-assembled InAs quantum dots in InP studied by space-charge spectroscopy and photoluminescence

In this paper, we report on a detailed investigation using junction space-c harge techniques and photoluminescence of InAs quantum dots embedded in an InP matrix. From measurements of thermal emission rates we have determined the ground-state energy of electrons and holes bound to the InAs dots. In c ontrast to other dot systems the holes are found to be more strongly confin ed than the electrons. Corresponding optical emission rates have been measu red for holes and the photoionization is found to be well described by a ph otothermal excitation process similar to what has previously been observed for deep impurities. Furthermore, we have performed photoluminescence measu rements revealing excited hole states with energies in good agreement with theory.