Fabrication and Optical Properties of Silicon Nanowires Arrays by Electroless Ag-catalyzed Etching

Jie Tang,Jianwei Shi,Zhongquan Ma,Lili Zhou

doi:10.1007/bf03353662

Abstract

Abstract In order to realize ultralow surface reflectance and broadband antireflection effects which common pyramidal textures and antireflection coatings can’t achieve in photovoltaic industry, we used low-cost and easy-made Ag-catalyzed etching techniques to synthesize silicon nanowires (SiNWs) arrays on the substrate of single-crystalline silicon. The dense vertically-aligned Si NWs arrays are fabricated by local oxidation and selective dissolution of Si in etching solution containing Ag catalyst. The Si NWs arrays with 3 μm in depth make reflectance reduce to less than 3% in the range of 400 to 1000 nm while reflectance gradually reached the optimum value with the increasing of etching time. The antireflection of Si NWs arrays are based on index-graded mechanism: Si NWs arrays on a subwavelength scale strongly scatter incident light and have graded refractive index that enhance the incidence of light in usable wavelength range. However, surface recombination of Si NWs arrays are deteriorated due to numerous dangling bonds and residual Ag particles.

Highlights

As a promising candidate for conventional fossil energy, high-efficiency and low-cost silicon photovoltaic devices still meet some challenges such as non-abundant utilization of solar spectrum [1] and various carrier recombination [2] in spite of rapid development over the past few decades
silicon nanowires (Si NWs) arrays were produced by Ag-catalyzed etching techniques on single crystalline Si substrates
The Ag particle film plated on the Si substrates is made up of dendrites-like structures and its arrangement causes the appearance of the pits and nanowires

Summary

Introduction

As a promising candidate for conventional fossil energy, high-efficiency and low-cost silicon photovoltaic devices still meet some challenges such as non-abundant utilization of solar spectrum [1] and various carrier recombination [2] in spite of rapid development over the past few decades. As discussed by Ogata [14], the plating of Ag catalysts in etching solution was a galvanic procedure in which the Ag ions input holes into the valence band of the Si wafer due to the difference of Fermi levels of these two substances and the reduced Ag particles formed nuclei in micro- or nanorange on the surface of the substrate. The surface and cross-sectional morphology of the sample etched as step III for 10 minutes are shown in Fig. 2(a) and (b).

Results

Conclusion