The Preparation And Property Study Of MgO/ZnO Thin Film

Magnesium oxide （MgO） has a good thermal and chemical stability and itsinsulating performance is excellent. Meanwhile, it’s lattice constant is close to commonfunctional thin films, such as PZT and YBCO. So it’s often used as the buffer lay for thecommon functional thin films deposited on Si substrate, which effectively alliveate thelattice mismatch and prevent the mutual diffusion. As the buffer layer, the crystallinequality of MgO directly affect the performance of the functional thin films. However,it’s hard to grow high-quality MgO thin film directly on Si substrate because of thelarge lattice mismatch （up to22.5%）. The ZnO underlayer was introduced to reduce theinterfacial stress generated by the large lattice mismatch between the Si and MgO.Firstly, c-axis oriented ZnO thin films were prepared on Si（100） substrate by RFreactive magnetron sputtering, then MgO thin films were deposited on Si and ZnO/Sisubstrates by DC reactive magnetron sputtering. The results from the x-ray diffraction（XRD） and atomic force microscope （AFM） analysis indicate that the introduction ofthe ZnO buffer layer greatly improve the crystalline quality of MgO thin film, while thethickness of ZnO buffer layer can fairly effect the structure and morphology of MgOthin film. The ZnO underlayer, with deposition time of25minutes and annealed byrapid thermal annealing （RTA） can play a better role as the buffer layer.In order to further enhance the quality of MgO thin film which deposited on ZnObuffer layer, the influence of substrate tempreture, power, pressure and the ratio of argonto oxygen on the structure and morphology of MgO thin films were disscussed. Theas-grown MgO thin films were annealed by the rapid thermal annealing （RTA） andconventional furnace annealing （CFA） to improve the quality of MgO. The results showthat both of the RTA and CFA treatment can greatly improve the quality of MgO thinfilm, but serious interdiffusion between the MgO and ZnO were oberved after annealedby CFA.The PZT overlay were deposited on MgO/ZnO by DC magnetron sputtering. XRDand AFM analysis show that the c-axis preferred PZT thin films with dense and uniformgrains, smooth surface are obtained. In order to test the electrical properties of PZT, the Pt electrode was introduced between the PZT and MgO. The P-E character and leakagecurrent of PZT thin films were characterized by ferroelctric tester, the polarization andleakage current of PZT thin film are21.42C/cm²and10^-610^-7Amps, respectively.