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The Effect of Etching Temperature upon the Optical Reflactance on Silicon Nanowires Grown By Electroless Etching
The antireflective nature of Silicon nanowires (SiNW’s) revealed by their black color and dull appearances have drawn the attention of researchers [1]. It may eliminate the need for antireflective coating on these nanostructures to reduce energy losses in solar cells [2]. SiNWs arrays prepared by electroless etching method can significantly suppress light reflection across the visible spectrum. Optical reflectance analysis on SiNWs fabricated at different temperatures (Fig. 1) show a significantly decrease in optical reflectivity down to 1.5% at 25°C.
Enhanced optical reflectance may be achieved at lower etching solution temperatures. Low temperatures slow the kinetics reaction that would grew uniform and well aligned SINWs (Fig. 2a) contrary to randomly direction nanowires grow at high temperatures (Fig. 2b). A uniform growing of SiNWs could optimize nanowire spacing that would improve charge collection and enhance optical reflectance [3].
In this experiment a Cary 100 UV-Visible Spectrometer was used for reflectance analysis and silicon (Si) wafers were dipped for 15 minutes at different temperatures (25°C, 35°C, 45°C, 55°C and 70°C) in an electroless solution prepared in a petri dish containing silver nitrate (AgNO3) and hydrofluoric acid (HF) [4].
