InP nanowire array solar cell with cleaned sidewalls

\u3cp\u3eWe have fabricated InP nanowire array solar cells with an axial p-n junction. Catalyst gold nanoparticles were first patterned into an array by nanoimprint lithography. The nanowire array was grown in 19 minutes by vapor-liquid-solid growth. The sidewalls were in-situ etched by HCl and ex-situ cleaned with a piranha etch. With this cleaning procedure, we could remove the sidewall extrusions and carbon contamination on the nanowire sidewall. We obtained a V\u3csub\u3eoc\u3c/sub\u3e of 0.68V, a fill factor of 71%, a diode rectification ratio of 10\u3csup\u3e7\u3c/sup\u3e, an ideality factor of 2.12, a solar cell efficiency of 10.2% and a >90% device yield.\u3c/p\u3