First-principles Study On The Heterostructure Of BaTiO₃-SiC

As a powerful rival of conventional Si-based structure, the ferroelectric-semiconductors with heterostructure have a great application potential in modern integrated ferroelectrics-based devices. This paper mainly studies on BaTiO3-SiC heterostructure consisting of classic ferroelectric and semiconductor materials with the help of first principle calculation software CASTEP, theoretically exploring its electronic properties in order to provide theoretical bases for future fabrications of ferroelectric-semiconductor-based nano devices.Firstly, this paper discusses surface structures of (001) BaTiO3 and several polar surfaces of SiC from three levels such as band structure, density of states, distribution of electron density, the fold parameters of the TiO2-terminated surface we calculate is 0.092 ? ,which is greater than that of the BaO-terminated surface. The surface energy of the TiO2-terminated surface is 1.21eV, which is also greater than 0.94 eV of the BaO-terminated surface. From them we can illustrate that TiO2-terminated surface is less stable due to dangling bonds of Ti atoms and its induced surface states. So TiO2 termination behaves good adsorption characteristics, thus is suitable for epitaxial growth of other thin films. Several polar surfaces of SiC are found quite different due to the differences of phase structures, atomic tenminations, polarization directions, and Si terminated satisfying the requirement of semiconductor processing.The relaxation parameterδz of the Si terminated surface is -6.524, it is much larger than -12.032, which is relaxation parameterδz of the C terminated surface. So the relaxation of C terminated surface is very large, but surface reconstruction could rarely occur. But reconstruction could occur on the Si terminated surface. Thus in this paper we choose Si terminated surface for the heterostructure.Then, we discuss the electronic properties of BaTiO₃-SiC heterostructure from its interfacial atomic structures, Band structures, PDOS, electron destiny, electron destiny difference, the bandgap of the heterostructure is 0.098eV There are apparent dislocations on the BaTiO₃ side. In the interface, Si and O have generated two different stable bonds and the bond length is 1.82 (?) and 1.83 (?). At last we calculate band offset and the result is 4.809eV. It shows that electrons in SiC atomic layers will be prevented from transmitting to BaTiO₃ side, providing possibilities for manufacturing ferroelectric-semiconductor heterostructure-based devices.