Study On The Electrical Characteristics And Energy Storage Performance Of HfO₂ Based Film Capacitor

With the increasing demand for integration and portability of the device,small-size data storage and energy storge devices emerge at the historic moment.However,there are many disadvantages in the application of traditional materials and structures,such as incompatibility with Complementary-Metal-Oxide-Semiconductor（CMOS）process for perovskite-type materials,difficulties in traditional chemical cells and fuel cells to achieve energy supply in small size devices due to the slow charging and discharging rate.All these problems seriously limit the further miniaturization and integration of devices.Binary oxide HfO₂ has been widely used due to its compatibility with CMOS process,the ferroelectricity and antiferroelectricity induced by doping in HfO₂ make this material have great potential application in data storage and energy storage.However,systematic research on the transport mechanism of HfO₂ in ultrathin films is still lacking,and the energy storage performance of HfO₂ is still not ideal in the research.Therefore,the main work and conclusions are as follows:1.The preparation process of La:HfO₂ thin films was explored,the surface morphologyof the film was tested,the structure and properties of the film were further tested and analyzed,and the origin of ferroelectric properties in La:HfO₂ films was analyzed.Finally,La:HfO₂ thin films with smooth surface and good ferroelectric properties were prepared.2.The conduction mechanism of Pt/La:HfO₂（4 and 8 nm）/La_0.67Sr_0.33Mn O₃ structure was studied.The band alignments of Pt/La:HfO₂/LSMO structure was measured by X-ray photoelectron spectroscopy and the conduction mechanisms are obtained by fitting temperature-dependent current-voltage curves from 50 to 300 K.In the 4 nm-thick La:HfO₂ thin-film capacitor,the conduction mechanism is found to be governed by direct tunneling at 50-100 K and phonon-assisted indirect tunneling when temperature is further increased to 300 K.In the 8 nm-thick La:HfO₂ thin-film capacitor,The transport for forward bias of the La:HfO₂/LSMO barrier is found to be governed by the thermionic-field emission,and for the reverse bias,the Fowler-Nordheim tunneling is observed,which is affected by La:HfO₂/LSMO interface barrier.3.The energy storage properties of Ba:HfO₂ thin film are studied.It is found that the amorphous Ba:HfO₂ thin film can be induced by precisely controlling the growth temperature and laser energy of the thin film.By changing the dopant content of Ba element,it can be observed that the transformation of fluorite-amorphous will occur in the film,and the appearance of this amorphous material can greatly improve the breakdown field of the film,so as to achieve high density energy storage characteristics.