In Situ Formation of Nanoporous Silicon on a Silicon Wafer via the Magnesiothermic Reduction Reaction (MRR) of Diatomaceous Earth.

Patrick Aggrey,Svetlana A Lipovskikh,Igor A Salimon,Yuliya Kan,Bakhodur Abdusatorov,Denis M Zhigunov,Alexander M Korsunsky,Alexey I Salimon,Sergey Luchkin

doi:10.3390/nano10040601

Abstract

Successful direct route production of silicon nanostructures from diatomaceous earth (DE) on a single crystalline silicon wafer via the magnesiothermic reduction reaction is reported. The formed porous coating of 6 µm overall thickness contains silicon as the majority phase along with minor traces of Mg, as evident from SEM-EDS and the Focused Ion Beam (FIB) analysis. Raman peaks of silicon at 519 cm−1 and 925 cm−1 were found in both the film and wafer substrate, and significant intensity variation was observed, consistent with the SEM observation of the directly formed silicon nanoflake layer. Microstructural analysis of the flakes reveals the presence of pores and cavities partially retained from the precursor diatomite powder. A considerable reduction in surface reflectivity was observed for the silicon nanoflakes, from 45% for silicon wafer to below 15%. The results open possibilities for producing nanostructured silicon with a vast range of functionalities.

Highlights

We focused on the direct formation of nanoporous silicon adherent layer on silicon wafer substrate through a direct reduction of reaction mixture (SiO2 + NaCl + Mg) on a silicon wafer substrate
Nanoporous silicon was successfully synthesized from diatomite powder via the magnesiothermic reduction reaction
The as-produced silicon nanoflakes reduced surface reflection of silicon wafer surface to values below 15%, reported a range of reflectivity for Black silicon (BSi)

Summary

Introduction

Facile fabrication of nano- or microporous silicon surface has been pursued over many years for potential applications in solar cells [1], lithium-ion batteries [2,3], microelectromechanical systems [4], H2 production by photo-electrochemical splitting of water [5], drug delivery [6], optoelectronic and photonic devices [7,8,9,10,11,12,13,14,15], and chemical and biological sensors [16,17,18,19,20]. Black silicon has been produced through techniques ranging from HF etching, stain etching, metal assisted chemical etching, laser irradiation, and the molten salt Fray–Farthing–Chen Cambridge (FFC Cambridge) process [1]. These techniques give positive results, a number of drawbacks have been reported. A possible metal contamination and subsequent thorough metal removal is required in the case of the metal-assisted chemical etching In both reactive-ion etching and laser treatment, a considerable amount of damage is made to the silicon substrate. Almost all the techniques presented in the literature to date require the removal of the top surface of the silicon wafer

Methods

Results

Conclusion