Enhanced Near-Bandgap Response in InP Nanopillar Solar Cells

The effect of nanopillar texturing on the performance of InP solar cells is investigated. Maskless, lithography-free reactive ion etching of InP nanopillars improves the open-circuit voltage, reduces reflectance over a broad spectral range, and enhances the near-bandgap response compared to a flat, non-textured cell with comparable reflectance in the infrared. Electron-beam induced current measurements indicate an increased effective minority carrier collection length. The response at short wavelengths decreases due to the formation of a defective surface layer with strong non-radiative recombination. Plasma oxidation and wet etching partially restore the blue response resulting in a power conversion efficiency of 14.4%.