In/ITO whisker and optoelectronic properties of ITO films deposited by ion beam sputtering

ITO films were deposited on a glass substrate using ion beam sputtering, with oxygen flow rates from 0.5 to 2 sccm. The films consisted of randomly oriented ITO nanoparticles and metallic indium (In) with {101} facets, following the specific crystallographic relationship of [010]In//[110]ITO; (001)In//(001)ITO with habit planes (100)In//(011)ITO, when fabricated using a low oxygen flow rate. Oxygen flow rate in excess of 2.0 sccm results in the growth of amorphous films. The epitaxial In nanoparticles probably act as seeds for the development of curved ITO whiskers as small as 10 nm and extend up to 100 nm in length along the [100] direction, with poorly defined shape, possibly due to the tapering and bending of the whisker to form a tilt boundary about the [011] zone axis of the ITO. The ITO whisker growth was facilitated by the In globular tips in the vapor–liquid–solid growth mechanism. The films prepared using a series of oxygen flow rates showed different chemical-bonding states, electric resistivity and optical transparency; as a result of phase and microstructural changes.