Anomalous tunneling effect on photoluminescence of asymmetric coupled double InGaN/GaN quantum wells

Tunneling-assisted carrier transfer in coupled double InGaN∕GaN quantum wells (QWs) has been studied by temperature-dependent photoluminescence (PL) at varied excitation density. It is found that the carriers captured by the wide (“deep”) well are efficiently transferred to the adjacent narrow (“shallow”) one by resonant tunneling, which results in anomalous temperature dependence of PL intensity and significantly enhanced luminescent efficiency for the narrow well. This is disparate from those conventional tunneling-assisted behaviors in coupled double QWs constructed by zinc-blende materials without polarization effect, where the carriers are always tunneling from the narrow (“shallow”) well to the wide (“deep”) one.