Simultaneous Growth of Nano and Submicrometer Sized ZnO Islands on Si and the Surface Electrical Properties

Simultaneous growth of two types of ZnO islands with different sizes has been observed on silicon substrate using radio frequency (rf) magnetron sputtering under an rf power of at substrate bias. Depositions were carried out using an (80:20) and gas mixture environment. The islands of the first type are well faceted, truncated pyramidal shaped ZnO islands on the Si surface with average base diameter and height . The other type is cone shaped ZnO islands with hemispherical base (upside down) which are embedded into the Si substrate. The size and height of the embedded ZnO cone shaped islands have been found to be in a range of and , respectively. These islands result from the bombardment of positive Ar ions into a negatively biased Si substrate. Morphology, shape, size, and microstructure have been investigated by transmission electron microscopy. Surface electrical properties of the bigger faceted ZnO islands have been measured by conductive atomic force microscopy. Enhanced current conduction has been found at the edges of the truncated pyramidal islands. This indicates that the nonpolar facets of and (10-11) are more electrically active than the polar facet of (0002).