First-principles calculations of carrier localization in fluctuated InGaN quantum wells

Abstract

The carrier localizations in c-plane and (2021) plane InGaN/GaN quantum wells (QWs) with structure fluctuations are investigated using firstprinciples calculations. The conduction band minimum (CBM) and valence band maximum (VBM) tend to localize in the region of high indium composition about both the c-plane QW and (2021) plane QW. In the case of the (2021) plane QW, the CBM and VBM can separate from each other in the in-plane direction as well as in the perpendicular direction, when fluctuations in indium composition or well width exist. The origin of the in-plane separation is the polarization charge generated by non-uniform piezoelectric polarization due to structure fluctuation in the InGaN QWs. Our results imply that the carrier separation in the in-plane direction originating from the structure fluctuation may contribute to lowering the light emission efficiency in semi-polar plane QWs.