Nanostructuring of InP by colloidal lithography and ICP etching for photovoltaic applications

We demonstrate a simple and cost effective method to fabricate InP nanopillars using silica particles as masks for etching InP. Oxygen plasma treatment of InP surfaces before dispersion of colloidal mask particles improved surface wettability significantly and helped in uniform coverage of the particles over large areas. Pillars with varied sizes were fabricated by dispersing colloidal SiO₂ with different sizes on the sample and/or by reducing size of particles after dispersion. Nanopillars with different heights and shapes from near cylindrical to conical were obtained by varying etch process parameters and by progressive erosion of colloidal SiO₂ particle (mask). Pillars with aspect ratios in excess of 15:1 have been obtained. Investigations are also made on regular close packed hexagonal structures with wide area coverage. Size reduction of colloidal particles after dispersion is used to overcome the lag effect observed in the etching of close packed structures. The demonstrated nanostructuring method is attractive for producing photonic crystals and antireflecting surfaces in solar cells.