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Porous silicon layers have been prepared from n-type silicon wafers of (100) orientation. SEM, XRD, FTIR, and PL have been used to characterize the morphological and optical properties of porous silicon. The influence of varying HF concentration in the anodizing solution, on structural and optical properties of porous silicon has been investigated. It is observed that pore size increases with HF:ethanol concentration ratio and attain maximum for 1:2 ratio and then decreases.

The conducting nature of nanocrystalline TiO 2 thin film coated on glass and silicon (Si) substrates was studied in detail. The films were prepared through sol-gel spin-coating method with variation in coating parameters viz, the thickness of the film and the post annealing temperature. The thickness of the films was measured using Stylus profilometer. The resistivity of the film, as a function of film thickness, under the illumination of UV, visible light, and dark conditions was found using the four-probe method. The results show that the resistivity of the film decreases with increase in thickness of the film. The decrease in resistivity of the film is attributed to increase in cross-sectional area and rearrangement and removal of defects. Illumination of the samples under visible and UV light further decreases the resistivity of the film. The electrical resistivity of TiO 2 film coated on Si substrate was observed to be lesser than that of the glass substrate.

Porous silicon (PS) layers have been prepared from n-type silicon wafers of (100) orientation. SEM, FTIR, and PL have been used to characterize the morphological and optical properties of PS. The influence of varying light illumination in the anodizing solution, on structural and optical properties of PS, has been investigated. It is observed that pore size increases with light illumination level, attains maximum for 17.5 mW/m2 and then decreases. The PL spectrum peak shifts toward the higher energy side, which supports the quantum confinement effect in PS. The FTIR shows that the Si – H n peaks are observed at the surface of the PS layer and these chemical species also give raise the PL in PS.