  Photoluminescence measurements on high-quality InGaN quantum wells reveal
that carriers diffuse laterally to long distances at room temperature, up to
tens of microns. This behavior, which shows a pronounced dependence on the
excitation density, contrasts with the common expectation of a short diffusion
length. The data is well explained by a diffusion model taking into account the
full carrier recombination dynamics, obtained from time-resolved measurements.
These observations have important implications for understanding the high
efficiency of III-nitride emitters, but also to properly interpret
photoluminescence experiments and to design efficient small-scale devices.
