Experimental Study of Design Parameters in Silicon Micropillar Array Solar Cells Produced by Soft Lithography and Metal-Assisted Chemical Etching

Solar cells, consisting of core-shell p-n junction silicon micropillars on a thin membrane fabricated using soft lithography and metal-assisted chemical etching, are studied as a function of geometrical designs. Significant enhancement in absorption rate is found without much dependence on the pillar diameters in the range of 0.5-2 mu m. However, the short-circuit current increases continuously with diameter, which is inversely proportional to the total surface area for a fixed diameter/pitch pillar array. This study provides unambiguous evidence that surface recombination is the dominant loss mechanism in nanowire- or micropillar-based solar cells.