Carrier dynamics in blue and green emitting InGaN MQWs

Spectrally and spatially‐resolved nonlinear optical techniques were combined with the photoluminescence spectroscopy to study carrier dynamics and photoluminescence efficiency in highly excited blue‐ and green‐emitting InGaN/GaN quantum wells. The differential transmission and transient grating techniques provided carrier lifetimes and diffusivity in the extended states with energies above the photoluminescence emission band and revealed their dependences on excess carrier density. At high excitation conditions, an increase of diffusivity led to the increase of nonradiative recombination rate, being more pronounced in the green QW structures with respect to the blue ones. Enhancement of these processes in the extended states has a strong impact on diminishing the photoluminescence efficiency in the localized states.