Thin porous silicon fabricated by electrochemical etching in novel ammonium fluoride solution for optoelectronic applications

A novel approach to electrochemically fabricate thin nanoporous silicon using ammonia fluoride solution is proposed and experimentally demonstrated. It is shown that highly uniform and thin nanoporous silicon layers (down to 50 nm) with high porosity can be formed in a reproducible manner under low current densities (0.01-0.1 mA/cm2) and low fluorine ion concentration (1%wt). Structural and opto-electrical properties of the porous silicon created in a wide range of current densities and ammonium fluoride concentrations are presented.