Structural, electrical and optical properties of nanocrystalline silicon thin films deposited by pulsed laser ablation

Nanocrystalline thin films of silicon (Si) were grown on glass substrates using pulsed laser deposition technique. Si nanoparticles thin films were investigated employing X-ray diffraction, field emission scanning electron microscopy, atomic force microscopy, low temperature electrical transport measurements, and UV–visible absorption spectroscopy. XRD data show that Si films are polycrystalline having cubic crystal structure with preferred (111) orientation. SEM and AFM micrographs exhibit dense and slightly rough surface morphology with well defined columnar grains. Temperature dependence of the resistivity has been fitted with ln ρ(T) ∞ T−1/4 which indicates three dimensional variable range hopping conduction mechanism as well as semiconducting behavior of films. Finally, the optical absorbance edge of Si thin films is described in terms of indirect transition model proposed by Tauc in the strong absorption region, and according to Urbach׳s rule in the medium absorption region.