(Invited) Emerging Applications of Nanostructured Porous Silicon

Abstract

Electrochemical anodization of single-crystalline silicon (c-Si) renders it porous via a self-organized propagation of nano- to micro-scale pores. Porous silicon (PS) layer fabricated under the appropriate process parameters consists of highly packed quantum-size nanocrystalline silicon (nc-Si) dots. Current topics on its application studies are discussed here. It is shown that the use of luminescent self-standing PS layers as a starting material for fragmentation is very effective to improve the fabrication yield of colloidal nc-Si dots. The efficiency of quasiballistic electron emission from an nc-Si diode is remarkably enhanced by using monolayer graphene as a surface electrode. Mask-less parallel lithography under an active-matrix drive and reductive thin film deposition have been developed. The non-resonant, broad-band, and low-distortion sound emission based on thermos-acoustic effect in nc-Si can reproduce complicated ultrasound signals. This is applicable to compact ultrasound source for analyzing ultrasonic communication mechanism between mice.