N. C. Das¹, N. K. Sahoo¹, D. Bhattacharyya¹, S. Thakur¹, N. M. Kamble¹, D. Nanda², S. Hazra³, J. K. Bal³, J. F. Lee⁴, Y. L. Tai⁴, C. A. Hsieh^4
1Applied Spectroscopy Division, Bhabha Atomic Research Centre, Mumbai 400085, India
²Coolant System Laboratory, Raja Rmanna Centre for Advanced Technology, Indore 452013, India
³Surface Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064, India
⁴National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Sience Park, Hsinchu 30076, Taiwan, R. O. C.

In the present work we have reported the results of investigations on local structures of e-beam evaporated (HfO₂-SiO₂) composite thin films by synchrotron based extended x-ray absorption fine structure measurements. It has been observed that for the composite film with 10% SiO₂ content, both Hf-O and Hf-Hf bond lengths are less than their values in pure HfO₂ film. However the bond lengths subsequently increase to higher values as the SiO₂ content in the composite films is increased further. It has also been observed that at the same composition of 10% SiO₂ content, the films have smallest grain sizes (as obtained from atomic force microscopy measurements) and highest refractive index (as obtained from spectroscopic ellipsometry measurements) which suggests that the e-beam evaporated HfO₂-SiO₂ composite films with 10% SiO₂ content leads to the most compact amorphous thin film structure.