Field-dependent carrier decay dynamics in strained<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">In</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Ga</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mi>−</mml:mi><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mi mathvariant="normal">N</mml:mi><mml:mo>/</mml:mo><mml:mi mathvariant="normal">G</mml:mi><mml:mi mathvariant="normal">a</mml:mi><mml:mi mathvariant="normal">N</mml:mi></mml:math>quantum wells

We have studied the effects of an external electric field on photoluminescence spectra and carrier lifetimes in strained ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}/\mathrm{G}\mathrm{a}\mathrm{N}$ quantum wells embedded in $p\ensuremath{-}i\ensuremath{-}n$ 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 $\ensuremath{-}30 \mathrm{V}.$ 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 $2.1\ifmmode\pm\else\textpm\fi{}0.2 \mathrm{M}\mathrm{V}/\mathrm{c}\mathrm{m}.$ 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.