Effect of Surface Termination on the Electronic States in Nanocrystalline Porous Silicon

Publisher Website
Google Scholar
Abstract
We report comparative studies of hydrogen-(H-PS) and deuterium-terminated porous Si (D-PS) nanostructures fabricated by electrochemical anodization with photochemical etching treatment. Experimental results show that the photochemical etching treatment can cause a blueshift of both the absorption and the photoluminescence of PS. However, D-PS shows a higher emission energy than H-PS in spite of the nanometer structure and the band gap energy being the same for both PS samples. These results can be understood by considering both the band gap upshift due to the quantum size effect and the energy reduction due to the coupling of the confined carriers to the surface vibration of terminated atoms on nanocrystals. Based on a tight-binding calculation, we argue that the difference of the emission energy can be understood in terms of the trapping of conduction electrons at the surface Si-H or Si-D bonds.