Field-dependent carrier decay dynamics in strained InxGa1-xN/GaN quantum wells

Abstract

We have studied the effects of an external electric field on photoluminescence spectra and carrier lifetimes in strained InxGa1-xN/GaN quantum wells embedded in p-i-n light-emitting diode (LED) structures. Two sample structures with x=0.15 for blue LED's and 0.2 for green LED's have been investigated, with increasing reverse bias up to -30 V. From spectrum-resolved photoluminescence, we observed region of blueshift and redshift in photoluminescence peak energies. From the energy shift, the strength of piezoelectric field was estimated to be 2.1+/-0.2 MV/cm. Within our bias range, we observed three orders and one order of magnitude changes in carrier lifetime, for blue and green LED's, respectively. These time-domain results are explained by escape tunneling and thermionic emission, together with carrier recombination which depends on the electron-hole wave function overlap change.