First Principles Study Of Batio <sub> 3 </ Sub>-zno Heterostructure Electronic Properties

As a powerful rival, ferroelectric-semiconductor heterostructure gives a great application potential in modern integrated ferroelectrics-based devices. This paper mainly studies BaTiO₃-ZnO heterostructure consists 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-sized devices.Firstly, this paper discusses in detail surface structures of (001) BaTiO₃ and several polar surfaces of ZnO from three levels such as band structure, density of states, distribution of electron density, in which TiO₂-terminated surface is less stable due to dangling bonds of Ti atoms and its induced surface states. In addition, TiO₂ termination behaves good adsorption characteristics, thus is suitable for epitaxial growth of other thin films. Several polar surfaces of ZnO are found quite different due to the differences of phase structures, atomic terminations, polarization directions, and Zn terminated surface is semiconducting for its large band gap of 1.803 angstrom, thus satisfying the requirement of semiconductor processing.Then simulations of adsorption process of ZnO molecular on BaTiO₃ (001) surfaces are approximately conducted based on molecular dynamics. Adsorptions on BaO termination is ill modulated by temperature field. In contrast, TiO₂ terminated surface behaves a particular adsorption mechanism under finite temperature for its intrinsic adsorption properties, in agreement to experimental results. Thus, TiO₂ termination acts as a suitable interface choice for modeling of BaTiO₃-ZnO heterostructure.Finally, we discuss the electronic properties of BaTiO₃-ZnO heterostructure from its interfacial atomic structures. Band offset calculations show that electrons in ZnO atomic layers will be prevented from transmitting to BaTiO₃ side, providing possibilities for manufacturing ferroelectric-semiconductor heterostructure-based devices. Then we continue to discuss the unique polarization reversal characteristics of BaTiO₃ material under electric field in order to explain the operation mechanism of ferroelectric random access memory, and at last, the importance of polarization coupling effect to improvement of performance of heterostructure is summarized.Experimental measurements are currently considered as the dominating procedure in the research area of ferroelectric-semiconductor heterstucture. However, the results mainly depend on environmental background such as experimental conditions and thus are inconvincible. Hence, the calculations in this paper provide new visions to current research on ferroelectric devices for giving an original and creative study on the electronics properties of BaTiO₃-ZnO heterostructure from theoretical level.