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Synthesis and photoluminescence study of silicon nanowires obtained by metal assisted chemical etching

Silicon nanowires (SiNWs) hold potential applications in optoelectronics and SiNW-based optical sensors. Here, a photoluminescence study of SiNW arrays fabricated with a simple two-step silver (Ag) catalyzed etching of silicon wafers is presented. The morphology and photoluminescence properties were investigated for SiNWs of different lengths obtained by varying Ag concentration (as silver nitrate, AgNO3) and etching time. The samples consist of vertically aligned SiNWs with length in the range ~10-40 µm. Our foremost result is that the photoluminescence intensity from the SiNW arrays is an order of magnitude higher than that from bulk Si. This is accompanied by a red-shift in the peak position of approximately 0.09 eV, which may be attributed either to the variation in size of the Ag-nanoparticles created during the etching process or different lengths of the SiNWs. The results indicate that SiNWs obtained by simple and cost-effective metal catalyzed etching, are potentially promising for optoelectronic applications.