Infrared photoluminescence from erbium-doped spark-processed silicon

The infrared (IR) photoluminescence (PL) of erbium-doped spark-processed silicon (sp-Si) was investigated. In addition to IR photoluminescence of undoped sp-Si (which peaks near 945 nm), the erbium insertion into the sp-Si matrix causes additional structure near 1540 nm, that is, in a wavelength range which is important for telecommunication purposes. Erbium was deposited on a silicon wafer followed by spark processing, which enables diffusion of some erbium into the SiOx matrix, thus achieving optoelectronically active spark-processed silicon. Rapid thermal annealing enhances the 1.54 mu m wavelength intensity. The optimal processing conditions that result in the most efficient photoluminescence have been established and are presented. In contrast to erbium-doped crystalline silicon, whose light emission is highly affected by temperature (10(3) times reduction in intensity when heating from 12 to 150 K), the intensity of erbium-doped spark-processed silicon decreases by only a factor of 4 when heated from 15 to 300 K. The room temperature PL efficiency was found to be 0.3% in contrast to erbium-doped crystalline Si whose PL efficiency is known to be 0.05%. The experimental findings are interpreted by postulating a photoluminescence mechanism with energy transfer from spark-processed silicon to the Er3+ ions and by light emission from intrashell energy transition from I-4(13/2)-> I-4(15/2). (c) 2006 American Institute of Physics.