Comparative study of quantum confinements effect present in Silicon Nanowires using absorption and Raman spectroscopy

Abstract Silver-induced chemical etching (SIE) has been widely explored for developing silicon (Si) based photovoltaic devices with its benefits for low-cost and large-area fabrication of silicon nanowires (SiNWs) of high aspect ratios. Structures and optical properties of SiNWs fabricated through chemical etching are significantly affected by experimental as well as environmental conditions of etching. A comparative study of quantum confinement (QC) effect due to variation in nano crystallite size (NCS) of SiNWs samples, fabricated by SIE technique has been investigated here using ultraviolet visible (UV-VIS) spectroscopy and Raman spectroscopy. An enhanced optical band gap has been observed from the samples under UV excitation at room temperature due to QC effect. To improve the understanding of basic mechanism of QC effect present in samples has been analyzed through characteristic features of Raman line-shape like red shift, asymmetry ratio and broadening as compared to its bulk counterpart. The NCS of SiNWs present in the samples has been calculated by QC based Brus model, bond polarizability (BP) model and Raman line-shape fitting model. This study prove itself to explore a new direction towards a systematic building block for fabricating optoelectronic devices based on light - matter interactions present at the nano-scale.