Preparations And Room-temperature Magnetism Analyses Of ZnO Based Diluted Magnetic Materials

Diulted magnetic semiconductors can realize many new multifunctional components by using the spin characteristic of electrons which consumes low energy and is easy to control.Among them,wurtzite ZnO is people's ideal choice in II-VI based DMS study and has been focus of attention because of its merits ,such as relatively low growh temperature,a large exciton binding energy of 60meV,a wide band gap of 3.27ev,and theoretical works predicted it can realize high-temperature FM.We first introduce the study about diulted magnetic semiconductors at present, especially the study about ZnO based DMS. In order to find a better method to prepare doping ZnO diluted magnetic materials,we prepared Cr doped ZnO films using multilayer-sputtering technique and magnetron cosputting technique ,and prepared Fe doped ZnO films using sol-gel method , studied the structure,component and magnetism of the samples. 1.Study on preparation methods(1)Cr-doped ZnO films of different concentration were prepared by multilayer-sputtering technique .RF sputtering power is about 175W, DC sputtering power is about 165W. The concentration is controlled by changing cosputting time of every layer(10s-30s).Through analyses, we found when the cosputting time of every layer is 20s and the concentration is 2%,the crystallization of the sample on silicon is the best,but the ferromagnetism of the sample on glass is the best .(2)Cr-doped ZnO films of different concentration were prepared by magnetron cosputting technique,RF sputtering power is about 175W, and DC sputtering power is changed from 10W to 48W to change the concentration. Through analyses,we found when the DC power is 24W and the concentration is 2%, the crystallization of the sample is the best ,but when the DC power is 10W and the concentration is 1%,the ferromagnetism of the sample is the best .(3)Fe-doped ZnO films were prepared by sol-gel method.The zinc acetate,2-methoxyethanol,ferrous choride were used as the raw materials.Through analyses,we found the crystallization of the samples on silicon prepared by dipping method is better.2.Study on room-temperature magnetism(1)When the preparing method is multilayer-sputtering technique,and the concentration is 2%,the magnetism of the sample on glass substrate is better than the sample's on silicon.Although they are prepared by the same method ,their structures can be different due to the different lattice mismatches of the different substrates.And the different distribution of doping ions may have some effect on their magnetism.(2)When the substrate is glass,and the concentration is 2%,the magnetism of the sample perpared by multilayer-sputtering technique is better than that prepared by cosputtering technique.Because when the preparing method is cosputtering technique,it can be more equably doped,and the sputtering power is lower,the samples prepared by different sputtering techniques can have different structures,and this can have some effect on their magnetism.(3)We analysed the room-temperature magnetism of Cr:ZnO films,and thought it's their nature, and it roots in the competition between antiferromagnetic interaction and ferrmagnetic interaction.