Abstract
The electronic structures of dangling bonds (DBs) at Ge/GeO2 and Si/SiO2 interfaces are explored by first-principles calculations. A comparative study of the DBs shows that the trigonal bonds of Ge around Ge-DBs are sharp, while those of Si around Si-DBs are planar. Moreover, the Ge-DB states do not lie near the midgap between the valence band top and conduction band bottom, while the Si-DB states clearly appear. These features are explained by the metallic properties of the bonding network of the Ge/GeO2 interface and agree with the different characteristics of the electron spin-resonance signals from these interfaces.