InP nanowire array solar cell with cleaned sidewalls

We 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_oc of 0.68V, a fill factor of 71%, a diode rectification ratio of 10⁷, an ideality factor of 2.12, a solar cell efficiency of 10.2% and a >90% device yield.