Fabrication of Luminescent Porous Silicon with Stain Etches and Evidence that Luminescence Originates in Amorphous Layers

Abstract

Stain films on Si wafers produced in solutions of HF:HNO3:H2O have been studied for over 30 years [1], and have been suggested [1] to be similar in nature to the anodically-etched porous Si films first demonstrated by Uhlir [2]. More recently, it was shown that stain films produced by etching Si in solutions of NaNO2 in HF and CrO3 in HF were similar in structure to porous Si films produced by anodic etching [3]. In fact, in the etching of Si by HF:HNO3:H3O solutions, the oxidation reaction chemistry is recognized to be the same as that of anodic oxidation, with points on the Si surface behaving randomly as localized anodes and cathodes [4]