  We examine the effect of carrier localization due to random alloy
fluctuations on the radiative and Auger recombination rates in InGaN quantum
wells as a function of alloy composition, crystal orientation, carrier density,
and temperature. Our results show that alloy fluctuations reduce individual
transition matrix elements by the separate localization of electrons and holes,
but this effect is overcompensated by the additional transitions enabled by
translational symmetry breaking and the resulting lack of momentum
conservation. Hence, we find that localization increases both radiative and
Auger recombination rates, but that Auger recombination rates increase by one
order of magnitude more than radiative rates. Furthermore, we demonstrate that
localization has an overall detrimental effect on the efficiency-droop and
green-gap problems of InGaN LEDs.
