Morphology-dependent optical properties of one-dimensional nanostructure-arrayed silicon

Abstract

The optical properties of one-dimensional nanostructure-arrayed silicon (1DNSASi), which was fabricated by the metal assisted electroless chemical etching method under different conditions, were characterized in the wavelength range of 220 — 1000 nm. Whether the optical absorption of the 1DNSASi was enhanced relative to that of the polished Si was determined from the detailed morphology of the 1D nanostructures. For the yellow 1DNSASi prepared at a high etchant concentration and high temperatures, its optical absorption was relatively nice in the ultraviolet light region, while a gradual attenuation was shown in the visible and the near-infrared regions, and the optical absorption was lower than that of the polished Si at wavelengths above 800 nm. When the effects of zeroth-order reflectance and zero transmission were combined, the optical absorption of the black 1DNSASi prepared at a low etchant concentration and room temperature was very high (> 99%) in the wavelength range of 220–1030 nm and displayed a slight decrease at wavelengths above 1030 nm. Our results demonstrate that the optical absorption of the black 1DNSASi could be further improved by increasing the etching depth and exhibited its measurable maximum value when the etching depth was large enough. These results indicate that the 1DNSASi may be a promising candidate for high-efficiency photovoltaic devices, high-sensitivity sensors and detectors.