Ultrafast carrier dynamics in highly implanted and annealed polycrystalline silicon films

Abstract

We have studied the ultrafast optical response of highly implanted and annealed polycrystalline silicon films. One-micron thin polycrystalline silicon samples-on-quartz implanted with As ions at a high dose of 2 × 10 16 cm-2 at 100 keV and annealed at various temperatures have been investigated using ultrafast pulses. Frequency doubled amplified femtosecond pulses at 400 nm have been used in a pump-probe configuration to measure the temporal reflective response from the polysilicon samples. A super-continuum of ultrafast laser pulses were generated and used in probing the samples at various wavelengths in the visible part of the spectrum. Transient reflection measurements reveal negative and positive contributions to the change in the index of refraction of the samples attributed to an increase in the carrier density and lattice temperature. Ion induced defects and subsequent annealing are key contributing factors in the dynamic behavior of these samples. © 2005 IOP Publishing Ltd.