Intense and stable blue-violet emission from porous silicon modified with alkyls

Abstract

An intense blue-violet band, centered at 3.0 eV, has been observed besides the red-orange band of the photoluminescence (PL) from the chemically modified porous silicon (PS) samples. The PS samples were formed on 30-50 Ω cm p-type (100) Si wafers by anodic etching at large current densities and then treated with 5-cyano-1-pentynes in toluene solution at 110-120°C. The intensities of the blue-violet lights increase with the increasing of the etching current densities, while the peak energies are hardly changed. The Fourier transform infrared spectra of the modified samples show that the alkyls have been bonded to the surfaces of the nanometer crystallite silicon particles. The decays of the blue-violet emission with a lifetime about 0.5 μs are different from the nanosecond lifetimes of the blue emissions in the oxidized PS samples reported before, and the 20 μs lifetimes of the concomitant orange PL bands. A carbon-compounds-related luminescence center has been proposed as the origin of this blue-violet PL band. © 2000 American Institute of Physics.