First-Principles Modeling and Calculations of HfO2/Si Interface in Nano Devices

Gate dielectric/substrate interface is crucial to the electrical performance of nano-devices. However, the investigation on characterization of interfacial atomic and electronic structures is still lacking. In this paper, first principles modeling and calculation were performed to investigate the atomic and electronic properties of the HfO2/Si interface. The optimized bulk models of Si and tetragonal HfO2 were combined to build the HfO2/Si interface with the assistance of Quantum Espresso software. Band structure and density of states were calculated based on the density functional theory (DFT). It was found that the weakly bounded oxygen moves towards the interfacial region obviously after relaxation which due to the strong interaction between interfacial Si and oxygen atoms. Chemical bonds at the HfO2/Si interface are easier to be broken than that of bulk atoms because interfacial bond length increases significantly. The additional interfacial states were generated after the construction of the interface. Our results reveal the mechanism of the changes between bulk models and the HfO2/Si interface from an atomic perspective, which is expected to be benefited to the performance optimization of electronic devices.