Evidence of type-I direct recombination in InP/GaP quantum dots via magnetoluminescence

Abstract

Photoluminescence from InP quantum dots within a GaP matrix is investigated as a function of magnetic field. By fitting the magnetoluminescence data to the energy states of the electrons and holes confined in quantum dots in a perpendicular magnetic field, the electron-hole reduced effective mass is determined to be 0.094m0. The diamagnetic shift in the luminescence peak gives an average exciton radius of about 5 nm, smaller than the dot radius. These results indicate that the recombining electrons are primarily composed of states originating from the InP Γ valley although the conduction band discontinuity between the InP and the GaP barrier is expected to be very small or even negative.