Microstructure and optical characterization of nanometric silicon films prepared by pulsed laser ablation

摘要

The effect of laser energy density, during pulsed laser ablation, on the microstructure and optical properties of silicon films has been investigated using techniques such as atomic force microscopy, scanning electron microscopy, X-ray diffraction, and UV–visible absorption/transmission spectroscopy. The thickness of prepared films increases with increase in laser energy density. The crystallite size and hence the crystallinity of prepared films have been estimated by X-ray diffraction and found to be dependent on laser energy density. The transmittance of films changes with laser energy density. The absorption coefficient of films has been found to be >10~4 cm~(?1) in wavelength region 450–1100 nm. The band gap of silicon films has been determined as 2.27, 2.11, and 1.90 eV corresponding to laser energy density of 1.5, 2.5, and 3.5 J cm~(?2), respectively.