Exploiting Polarization Charges for High-Performance (000-1) Facet GaN/InGaN/GaN Core/Shell/Shell Triangular Nanowire Solar Cell

In III-nitride nanowire (NW)-based solar cells, efficient utilization of polarization charges is essential in order to achieve high performance. In this paper, the polarization behavior of a GaN/In
_x
Ga
_1-x
N/GaN core/shell/shell triangular NW solar cell with {000-1} or {0001} as one of the facets is intensively studied through numerical simulations. An analysis of defect density, strain profile, and polarization charges at different facets of NWs with different “In” compositions is considered carefully. It is observed that an NW solar cell with a N-polar {000-1} facet is good enough to enhance carrier collection efficiency as compared with Ga-polar {0001} facet. This numerical study provides an innovative aspect of implementation of fundamental device physics with respect to recent growth techniques in order to realize the application of III-nitride NWs toward photovoltaic applications. The effect of an In
_x
Ga
_1-x
N layer with different “In” compositions in all crystallographic orientations of NW solar cells is also discussed. It is interesting to observe that a maximum conversion efficiency of ~3.85% with the 93.38% fill factor is achieved from an n-GaN/i-In
_x
Ga
_1-x
N/p-GaN nanowire solar cell considering 10% of “In” content under one Sun AM1.5 illumination.