Study On Preparation Of Doped ZnO Magnetic Films

Since the spintronics was produced it has brought in great changes occurred for the electronics filed. It uses the spin character and charge character simultaneously, people have designed and developed many new electronic spintronics devices according to its two characters. Diluted magnetic semiconductor(DMS) is an important part of spintronics devices ,it has become the focus of study in the recent years. It uses transitive metal to doped in the non-magnetic material, and the transitive metal replaces partial cations of the non-magnetic material, then it becomes a new material. Recently more and more people begin to investigate the DMSs because it has good electrical characters,magnetic characters,optical characters and it also has excellent gas sensing property and piezoelectric property. Many persons have obtained the room temperature ferromagnetism, but the origin of the ferromagnetism exists controversy. Some people think that the ferromagnetism is from the clusters and second phase, while there are also many people consider that it was the nature of the films. This paper prepared Fe doped ZnO films by magnetron co-sputtering method and sol-gel method, we investigate the influence of the surface and magnetism of the films prepared by different methods,and we change the parameters of the magnetron co-sputtering method to research the influence to the films'magnetism with different prepared parameters. We tested the films by SEM,XRD,XPS,PL,and measured the magnetism by PPMS. Our main research contents as follow:1. We prepared the films by sol-gel method ,and the Fe doping concentration were 0,1%,3%,5%. We found all the films have several diffraction peaks,and we did not find the second phase by XRD tested.We detected the Fe incorporates the ZnO crystal lattice asFe3+. We got the biggest saturation magnetization(Ms) when the doping concentration was 1% by PPMS.We got different Ms at different magnetic filed, this phenomenon illustrated the films were anisotropic magnetization, this was also a evidence that the magnetism is form the film itself.2. We changed the Fe doping concentration by controlling the Fe sputtering power when we prepared the films by co-sputtering method,all the films have good c-axis orientation . We obtained the biggest Ms=0.49μB/Fe when the Fe sputtering power is 40W。3. We prepared films at the substrate temperature were room temperature,250℃,400℃,500℃,when the substrate temperature was 400℃the grain size was uniform, and we got the biggest Ms= 0.64μB/Fe。4. We chose the Fe sputtering power was 40W, substrate temperature was 400℃, and we made the films annealed in the vacuum and oxygen atmosphere, we found the Ms of the film annealed in the vacuum is bigger than the film that was not annealed, and the Ms was decreased when it was annealed in the oxygen atmosphere. This illustrated that the O vacancy could influence the magnetism of the films.