Sign reversal of visible to UV photocurrent in core-shell n-InGaN/p-GaN nanowire photodetectors

We demonstrate the change of the sign from negative to positive of the self-powered photovoltaic photocurrent in core-shell n-InGaN/p-GaN nanowire heterojunctions within the visible to UV wavelength range. Such dual-polarity photodetectors are of broad interest to provide extended functionalities for optoelectronic devices, starting with dual-wavelength photodetectors. The physics of the photocurrent sign reversal is understood by a well-balanced selective absorption and photocarrier generation, photocarrier transfer, and thermal excitation paths in the core-shell n-InGaN/p-GaN nanowire functional absorber with different bandgap energies and opposite inner- and surface energy band bendings. The basic dual-wavelength photodetector operation parameters are given.