Below gap photon induced photocurrent enhancement in GaPN intermediate band solar cell fabricated by ion implantation

Abstract This work describes the enhancement of photogenerated current through two-step absorption of below-gap excitation (BGE), attributed to the existence of tail states within the band gap of ion-implanted GaPN alloy, as measured using the two-wavelength excited photocurrent measurement technique. The absorption of BGE light contributes to a rise in external quantum efficiency and photocurrent density, with a more pronounced effect in the energy region where the tail states density is higher. The results in this study are comparable to those of epitaxially grown GaPN intermediate band solar cells (IBSCs), suggesting that ion implantation can be a feasible alternative for fabricating diluted nitride IBSCs.