Structural and optical properties of silicon oxycarbide thin films using silane based precursors via sol-gel process

Abstract

Silicon oxycarbide (SiCxOy) is a candidate material for white luminescence. This work investigates the formation of SiCxOy thin film coating by sol-gel route using various silanes namely, methyltrimethoxy silane (MTMS) with or without using tetraethyl orthosilicate, vinyltrimethoxysilane and polydimethyl siloxane, followed by calcination at 1000 °C/1 h under Ar atmosphere. The structural and optical properties of the developed films were studied by X-ray diffractomete (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), electron paramagnetic resonance (EPR) spectroscopy and Photoluminescence (PL). XRD plot shows amorphous nature of silicon oxycarbide (SiCxOy) while FTIR reveals Si-C band at 795 cm−1 and Si-O-Si band at 1085 cm−1 confirming the presence of SiCxOy. XPS analysis of MTMS derived coating revealed stoichiometry of SiC0.3O2.25 which is comparable to SiCxOy (0.2<x<0.6, y<1.6). EPR spectra analysis shows presence of Si-dangling bond which could be the probable cause of luminescence center in SiCxOy as observed from PL study. FESEM shows uniform coating of thickness ∼200 nm. PL spectra shows blue and green emission peaks at ∼ 403–452 and ∼ 483–560 nm, respectively.