Optical assessment of silicon nanowire arrays fabricated by metal-assisted chemical etching
1 Department of Physical Electronics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan
2 PRESTO, Japan Science and Technology Agency (JST), Honcho, Kawaguchi, Saitama 332-0012, Japan
3 Photovoltaics Research Center (PVREC), Tokyo Institute of Technology, Tokyo 152-8552, Japan
4 Advanced Materials Laboratory, Nissan Research Center, Kanagawa, Yokosuka 237-8523, Japan
Nanoscale Research Letters 2013, 8:216 doi:10.1186/1556-276X-8-216Published: 7 May 2013
Silicon nanowire (SiNW) arrays were prepared on silicon substrates by metal-assisted chemical etching and peeled from the substrates, and their optical properties were measured. The absorption coefficient of the SiNW arrays was higher than that for the bulk silicon over the entire region. The absorption coefficient of a SiNW array composed of 10-μm-long nanowires was much higher than the theoretical absorptance of a 10-μm-thick flat Si wafer, suggesting that SiNW arrays exhibit strong optical confinement. To reveal the reason for this strong optical confinement demonstrated by SiNW arrays, angular distribution functions of their transmittance were experimentally determined. The results suggest that Mie-related scattering plays a significant role in the strong optical confinement of SiNW arrays.