Effect of Hydrogenation on the Optical Properties of Cobalt and Tantalum Thin Films

Mangej Singh


Thin films of cobalt are prepared using thermal evaporation method at pressure 10-5 torr. The hydrogen gas is introduced in chamber at different pressure from 0 Psi to 40 Psi to hydrogenate the films. Optical transmission is found to increase and optical absorption decrease with hydrogenation. The optical band gap in Co thin film is found to reduce with increasing of hydrogen pressure. The relative resistance in the Co thin films is also measured at different hydrogen pressures. It is found to vary nonlinear with increase in hydrogen pressure. The Raman Spectroscopy data show that intensity of Raman peaks is decrease with hydrogen pressure. The prepare film after hydrogenation shows the switchable behavior with variable optical band gap. The variation in optical band gap suggests electronic structural phase changes in thin films with hydrogenation. The surface morphology is carrying out for these films with and without hydrogenation by using optical microscope and Scanning Electron Microscope (SEM). Thin films of tantalum also prepared by using DC Sputtering unit and then hydrogenation at pressure 10 Psi. Transmission spectra and surface morphology also carry out for these films before and after hydrogenation. The optimum thickness for switchable mirrors observed was 170.5 nm in case of tantalum.


Optical absorption; Transmission; Optical energy band gap; Surface Morphology; Resistivity

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DOI: http://dx.doi.org/10.3968/j.est.1923847920130502.858


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