Anti-Stokes photoluminescence of InP self-assembled quantum dots in the presence of electric current

An intense anti-Stokes photoluminescence was observed in a structure with InP quantum dots (QD's) in the presence of both a direct electric current and optical pumping below the lowest electron-hole transition in quantum dots. The discovered phenomenon provides clear evidence of deep energy levels in the vicinity of the QD's. A simple model was proposed which allowed us to estimate the energies of the deep states and the lower limit of the product of the electron and hole relaxation rates from the QD's to the deep states.