  Oblique angle deposited oxide thin films have opened up new dimensions in
fabricating optical interference devices with tailored refractive index profile
along thickness by tuning its microstructure by varying angle of deposition.
Microstructure of thin films strongly affects surface morphology as well as
optical properties. Since surface morphology plays an important role for the
qualification of thin film devices for optical or other applications, it is
important to investigate morphological properties. In present work, HfO2 thin
films have been deposited at several oblique angles. Morphological statistical
parameters of such thin films viz., correlation length, intrinsic roughness,
fractal spectral strength, etc., have been determined through suitable
modelling of extended power spectral density function. Intrinsic roughness and
fractal spectral strength show an interesting behaviour with deposition angle
and the same has been discussed in the light of atomic shadowing, re-emission
and diffusion of ad-atoms. Further refractive index and thickness of such thin
films have been estimated from transmission spectra. Refractive index and grain
size depict an opposite trend with deposition angle and their variation has
been explained by varying column slanting angle and film porosity with
deposition angle.
