Effect of substrate temperature on structural and linear and nonlinear optical properties of nanostructured PLD a-SiC thin films

• Nanostructured a-SiC of different stochiometry have been fabricated by PLD.
• Shift in stochiometry from Si-rich to nearly stochiometric SiC with increasing Ts.
• Stochiometry dependent tunable optical bandgap in a-SiC.
• Films showed self focusing and reverse saturation absorption under cw He-Ne laser.
• Optical χ(3) obtained was 107 times than that of reported in bulk SiC crystal.

In this paper, the effect of substrate temperatures (Ts) on the structural, linear and non-linear optical properties of nanostructured amorphous Silicon Carbide (a-SiC) thin films deposited onto fused silica by pulsed-laser deposition technique is reported. The structural and compositional properties were studied by X-ray diffraction, Raman spectroscopy and Fourier transform Infrared spectroscopy. A transition from Silicon-rich SiC to nearly stoichiometric SiC was observed with increasing Ts. The absorption coefficient (α), refractive index (n), optical band gap and thickness of the films were determined from UV–vis-IR spectra. Static refractive indices of the films were found to vary from 2.99–2.54 with the increasing Ts. The optical band gap of the films was found to be increasing from 1.5 eV to 2.33 eV with increase in Ts. The third order non-linear optical susceptibility (χ(3)) of the a-SiC thin films estimated from Z-scan studies was found to be of the order of 10−3 esu.

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