Electron Energy-Loss Near-Edge Structures For CoSi₂/Si Thin Film:Ab Initio And Experimental Study

Jia-An Lin^1*, Chia-Yi Wu¹, Yi-Chia Chou¹

¹Department of Electrophysics, National Yang Ming Chiao Tung Univeristy, Hsinchu, Taiwan

* Presenter:Jia-An Lin, email:ann.lin.07@gmail.com

We studied the interfacial electronic structure of CoSi₂/Si(100) thin film using electron energy loss spectroscopy (EELS) and Vienna Ab Initio Simulation Package (VASP) based on density-functional theory. EELS was acquired from an epitaxial CoSi₂ grain across the CoSi₂/Si interface, and the ab initio calculations were performed on a well-defined CoSi₂/Si heterostructure. The resultant unoccupied density of states was compared with the experimental core-loss spectra, providing an insight into the CoSi₂/Si interfacial electronic structure according to its characteristic near-edge structures. The substrate Si p orbital partial density of states (PDOS) at the CoSi₂/Si interface revealed that new states appeared near the Fermi level. Furthermore, substrate Si p-PDOS at the CoSi₂/Si interface decreased and slightly shifted to higher energy comparing with bulk Si, implying new bond formation at the interface. On the other hand, Co d-PDOS at the CoSi₂/Si interface showed a double peak around 2 eV and 4 eV above the Fermi level respectively, instead of a broad peak and a sharp peak typical for bulk CoSi₂. Such findings could be represented as the characteristic near-edge structures of CoSi₂/Si interface.

Keywords: silicide, heterostructure, electron energy-loss spectroscopy, first principle calculations, density of states