Imagings of Picosecond-Photoexcited Carriers and Enhanced Auger Recombination Rate by Transient Reflecting Grating Measurements

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Abstract
Photoinduced dynamic processes at a silicon surface were investigated by time-resolved measurements of a transient reflecting grating with 532 nm excitation and detection. The signal caused by photoexcited carriers was separated from signals due to thermal and acoustic effects. The carrier signal was found to be more sensitive to ion induced damages than the thermal and acoustic effect signal. Use of the carrier signal provided an in-plane distribution image of near surface damage induced by helium ion implantation (energy, 200 keV; dose, 1015 atoms/cm2). The cause of the contrast formation was found to be the change of Auger recombination rate γ3. The obtained γ3 for intrinsic silicon was 4.0×10-29 cm6/s which was two orders of magnitude larger than the bulk value. The results indicated defects near the surface region ( ∼100 nm) accelerated γ3.