Selective electrochemical deposition of indium in-between silicon nanowire arrays fabricated by metal-assisted chemical etching

Abstract

Indium electrodeposition in-between silicon nanowire arrays fabricated by silver-assisted chemical etching of lightly-doped (100)-oriented silicon wafers is evaluated. It is concluded based on SEM and EDX analysis of indium's distribution that, by utilizing pulsed-mode electrodeposition and maintaining a sufficiently low duty cycle value, indium particles can be formed exclusively at the very bottom of each consecutive pore on the residual silver particles left over from metal-assisted etching. This result differs significantly from irregular pore filling along with surface and subsurface deposition observed in the cases of continuous galvanostatic deposition regimes at prolonged durations or in the absence of residual silver particles. Bottommost fusible metal deposit localization, which is unattainable on porous silicon fabricated by electrochemical anodization, is presumed to be optimal for the growth of germanium crystallites inside the pores via the electrochemical liquid-liquid-solid approach and subsequent silicon-germanium alloy formation through thermal annealing.