Electroless Chemical Grafting of Nitrophenyl Groups on n-Doped Hydrogenated Amorphous Silicon Surfaces

The direct spontaneous grafting of 4-nitrophenyl molecules onto n-doped hydrogenated amorphous silicon (a-Si: H) surfaces without external ultraviolet, thermal, or electrochemical energy was investigated. Clean n-doped a-Si: H thin films were dipped in a solution of 4-nitrobenzenediazonium salts (PNBD) in acetonitrile. After the modified surfaces were rinsed, they were analyzed qualitatively and quantitatively by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). XPS and AFM results show that the reaction of an n-doped a-Si: H thin film with PNBD self-terminates without polymerization after 5 h, and the surface number density of 4-nitrophenyl molecules is 4.2x10(15)/cm(2). These results demonstrate that the spontaneous grafting of nitrophenyl layers onto n-doped a-Si: H thin films is an attractive pathway toward forming interfaces between a-Si: H and organic layers under ambient conditions.