Electronic structure of germanium nitride considered for gate dielectrics

Abstract

First-principles calculations based on density-functional theory and the local-density approximation have been used to investigate structural, electronic, and optical properties of α, Β, and γ phases of germanium nitride (Ge3 N4). Β- Ge3 N4 was found to be the most stable among the three structures, and it has a very small lattice mismatch with Ge, which indicates that it could be grown epitaxially on Ge. The calculated band gaps of α -, Β -, and γ- Ge3 N4 are about 3.15, 3.07, and 2.33 eV, and the corresponding static dielectric constants are 4.70, 4.74, and 6.27, respectively, within local-density approximation. Results of our calculations indicate that the band gap and static dielectric constants of Ge3 N4, as well as Si3 N4, could satisfy the requirements of gate dielectrics for Ge-based field effect transistors. © 2007 American Institute of Physics.