Study of Sm-doped ZnO samples sintered in a nitrogen atmosphere and deposited on n-Si(1 0 0) by evaporation technique

The samarium doping zinc oxide (Zn_1-xSm_xO) with (x=0.0, 0.04, 0.05 and 0.17) polycrystalline thin films have been deposited on n-Si(1 0 0) substrate using thermal evaporation technique. Ceramic targets for deposition were prepared by the standard solid-state reaction method and sintered in nitrogen atmospheres. X-ray diffraction and scanning electron microscopy analyses show that the bulk and films features reveal wurtzite crystal structure with a preferential (1 0 1) crystallographic orientation and grows as hexagonal shape grains. According to the results of the Hall effect measurements, all the films show p-type conductivity, possibly a result of nitrogen incorporation into the Sm-doped ZnO samples. Magnetic measurements show that ferromagnetic behavior depends on the Sm³⁺ concentration. For a film with lower Sm₂O₃ contents (x=0.04), a phenomenon of paramagnetism has been observed. While, with further increase of Sm³⁺ contents (x=0.05) the ferromagnetic behavior has been observed at room temperature. However, at higher doping content of Sm³⁺, the ferromagnetic behavior was suppressed. The decrease of ferromagnetism with increasing doping concentration demonstrates that ferromagnetism observed at room temperature is an intrinsic property of Zn_1-xSm_xO films.