Electrophotoluminescence in Semiconductors

Abstract

Four electric-field effects on photoluminescence have been observed in the low-temperature green-edge emission in GaP. These are the Gudden-Pohl effect, field quenching, field enhancement, and field broadening of the emission band. From independent evidence the edge emission is known to result from the reaction between electrons bound to donor impurities (sulfur) and holes bound to acceptor impurities (silicon). The data are explained on a semiquantitative basis, in terms of these donor-acceptor pairs, using a refined version of a previously described theoretical model in which it is not necessary to invoke trapping or detrapping from traps of known or unknown origin. The theoretical model employs hydrogenic impurity wave functions, and as before leads to the observed nonexponential time decay of the photoluminescence. The electric-field effects are taken care of by considering the action of the field on the impurity wave functions, using a WKB approximation.