Field-dependent carrier decay dynamics in strained ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{N}/\mathrm{G}\mathrm{a}\mathrm{N}$ quantum wells

We have studied the effects of an external electric field on photoluminescence spectra and carrier lifetimes in strained ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{N}/\mathrm{G}\mathrm{a}\mathrm{N}$ quantum wells embedded in $p-i-n$ light-emitting diode (LED) structures. Two sample structures with $x=0.15\mathrm{}$ for blue LED’s and 0.2 for green LED’s have been investigated, with increasing reverse bias up to $-30\hspace{0.5em}\mathrm{V}.$ 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 $2.1\pm 0.2\hspace{0.5em}\mathrm{M}\mathrm{V}/\mathrm{c}\mathrm{m}.$ 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.