Violet and Blue Light Emissions from Nanocrystalline Silicon Thin Films

Abstract

Nanocrystalline silicon thin films with a grain diameter from three to seven nanometers were fabricated on silicon substrates. It is demonstrated for the first time that the thin films show intense violet and blue luminescence at room temperature. The luminescence spectra include three peaks at wavelengths of 415 nm, 437 nm and 465 nm. Anodizations of these thin films introduce additional green and red luminescence in the spectra. Fourier transform infrared spectroscopy indicates no hydrogen- or oxygen-related absorptions in the nanocrystalline silicon thin films. Only the anodized thin films show Si–H _x absorptions. The violet luminescence should be evidence of light emission from zero-dimensionally confined silicon structures.