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-charge 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 contrast to other dot systems the holes are found to be more strongly confined than the electrons. Corresponding optical emission rates have been measured for holes and the photoionization is found to be well described by a photothermal excitation process similar to what has previously been observed for deep impurities. Furthermore, we have performed photoluminescence measurements revealing excited hole states with energies in good agreement with theory.