Pulsed Electron Beam Based Fabrication And Measurements Of Ba TiO₃ Ferroelectric Nanometer Film On Silicon Substrate

Nowadays,people have made great development in microelectronic integrated circuit.Also,more photoelectric devices and sensors are becoming smaller and smaller.These above all make the ferroelectric films become more popular because of its special ferroelectric properties.As a result,the ferroelectric films bring us more regulatory mechanisms and applies.However,the mostly used ferroelectric films are not ‘lead-free',as we all know they are not environmentally friendly.People have spent the last ten years to find ‘lead-free' ferroelectric material.Hence,in this paper we studied on barium titanate(Ba Ti O3,BTO)-a ‘lead free' ferroelectric material.BTO thin films have good ferroelectric properties,piezoelectricity,highly non-linear optical activity and so on.Among all the studies focused on growing BTO thin films,we found out that the thickness of BTO thin films prepared is always more than 100 nm,and most of them are deposited on silicon with strontium titanate(Sr Ti O3,STO)thin film on it or other functional materials,they are also deposited on substrate with metal electrode on it when it comes to test the ferroelectric property of BTO thin films.In this paper,we prepared BTO thin films with thickness beneath 30 nm by PED on single crystal silicon substrate,and studied the influences of deposition conditions on the properties of BTO thin films.The main work and achievements are as follows:We firstly deposited BTO thin films on single crystal silicon substrate with PED,and studied the properties of BTO thin films.Through the use of PED,we got BTO thin films with thickness beneath 30 nm.Then we characterized the morphology of BTO thin films with scanning electron microscopy(SEM)and atomic force microscopy(AFM).The films turned out to be flat and uniform.X-ray diffraction was used here to prove the crystallinity of BTO thin films was good.By using piezoresponse force microscopy,we could observe microcosmic electric domains in BTO thin films.We obtained very good ferroelectric property in our prepared BTO thin films under an optimized deposition temperature of 700 ? with a thickness of 23.6 nm.And the ferroelectric property became better because the thickness grown.The effect of non-in-situ heat treatment on the properties of BTO thin films was also studied.It was found that the annealed BTO thin films prepared by PED could reduce the anoxic condition in the BTO thin films,and improve the crystallinity and microcosmic electric domains of BTO thin films.