Effect of implantation of Sm+ ions into RF sputtered ZnO thin film

Abstract

The effects of implantation of Samarium ions (Sm+), a rare earth ion (RE) on the properties of ZnO films grown on Si (001) substrate by RF sputtering system are presented. The structural properties of the virgin and Sm–implanted ZnO thin films were investigated by Atomic force microscopy, Rutherford backscattering spectroscopy and Raman spectroscopy. Local lattice softening caused by the incorporation of highly mismatched Sm+ (ionic radii 0.096 nm and 0.113 nm for Sm3+ and Sm2+ respectively) into Zn antisites was detected as a red shift in E2 (high) mode likely caused by reduction in the crystallinity of the ZnO film. Photoluminescence on the pristine ZnO film showed a strong near band gap (NBE) emission and an intrinsic defect related blue, green-orange emission. The NBE is suppressed after implantation of Sm+ while the blue, green – orange emission intensities are enhanced as a result of increased structural defects with mismatched charge states. Moreover the effect of varying the concentration of Sm+ ions is presented and compared with predictions made from Stopping and Range of Ions in Matter (SRIM) calculation.