Ion beam modification of Transparent Conducting Oxide (TCO) thin films by keV ions

Abstract

In this work, ion beam induced modi cation in ITO and ZnO thin lms of thickness 100 and 120 nm, respectively, used in spin based magnetoelectronic and optoelectronic nanodevices have been studied. These lms were implanted by Co+ and V+ ions at di erent energies. The implanted lms have been characterized by di erent material characterization techniques, and the e ects of transition metal ion implantation on their properties have been investigated. Lattice parameters showed interesting changes while the transmittance of thin lm implanted at 1 1016 ions/cm2 increased to 82.34 %. An increase in bandgap was observed with increase in ion uence from 0 to 1 1016 ions/cm2. The thin lm implanted to 5 1016 ions/cm2 showed decreased in roughness with root mean square (Rq) roughness of approximately 17.4 nm, and the grain size decreases to 4.59 nm. It was found that low thermal factor a ects the stability of implanted lms by 15.70 %. In Co+ ion implanted RF - magnetron sputter deposited zinc oxide thin lms, the lattice strain was observed to decrease by 10.92 %, while grain size increased by 34.82 % at high ion uence. Hence, ion implantation enhanced the mechanical strength of ZnO. The optical band gaps of implanted samples showed interesting improvement. The crystalline quality of ITO thin lms was observed to be enhanced upon implantation. It was found that the Co+ ion implanted ITO thin lms have good ability to retain a certain amount of residual magnetic eld at zero magnetizing force, as ion uence increases. The Co+ ion implanted ITO thin lms were found to exhibit clear room temperature ferromagnetism. The shift in hysteresis loops along applied magnetic eld axes provides information about the exchange bias on as-grown and Co+ ion implanted ITO thin 3 lms in relation with grain size. At low ion uence, a sharp increase in conductance was recorded. Therefore, the modi cation of ZnO and ITO thin lms eventually leads to enhanced properties. Co+ and V+ ion implanted ZnO and ITO thin lms have potential applicability in optoelectronics, spin based magnetoelectronic and energy nanodevices.