Effect of electron beam rapid thermal annealing on crystallographic, structural and magnetic properties of Zn 1−x Sm x O thin films

Abstract

Abstract Trivalent rare earth ions (Sm 3+ ) doped ZnO dilute magnetic semiconductor thin films (Zn 1− x Sm x O, where x =0.02, 0.04 and 0.06) of different thickness are grown on silicon (100) substrates using radio frequency magnetron sputtering and post annealed in high vacuum by electron beam rapid thermal annealing (ERTA) technique. X-ray diffraction analysis indicates that the thin films have a ZnO's hexagonal wurtzite structure. The unit cell constants a, c and the cell volume increases in the as-deposited sample as ‘ x ’ increases, whereas ERTA has a reverse effect on them. Topographic analysis by atomic force microscopy on as-deposited thin films shows nonlinear change in grain size as a function of Sm concentration, whereas annealed thin films show linear change. Magnetization studies by vibrating sample magnetometer on as-deposited and annealed Zn 1− x Sm x O thin films show ferromagnetic response, due to the oxygen vacancies introduced by Sm doping. The as-deposited 100 nm Zn 0.94 Sm 0.06 O thin film is weakly ferromagnetic (24 µemu), which after annealing becomes comparatively stronger (60 µemu). This indicates that apart from higher doping concentration of Sm, ERTA plays an important role in inducing oxygen vacancies.