Microstructure of femtosecond laser-induced grating in amorphous silicon

The femtosecond laser-induced grating (FLIG) formation and crystallization were investigated in amorphous silicon (a-Si) films, prepared on glass by plasma-enhanced chemical-vapor deposition. Probe-beam diffraction, micro-Raman spectroscopy, atomic force microscopy, scanning electron microscopy, and transmission electron microscopy were employed to characterize the diffraction properties and the microstructures of FLIGs. It was found that i) the FLIG can be regarded as a pattern of alternating a-Si and microcrystalline-silicon (microc-Si) lines with a period of about 2microm, and ii) efficient grating formation and crystallization were achieved by high-intensity recording with a short writing period.