First-principles study to obtain evidence of low interface defect density at Ge/GeO2 interfaces

We present evidence of low defect density at Ge/GeO2 interfaces on the basis of first-principles total energy calculations. The energy advantages of atom emission from the Ge/GeO2 interface to release stress due to lattice mismatch are compared with those from the Si/SiO2 interface. The advantages of Ge/GeO2 are found to be less than those of Si/SiO2 because of the high flexibility of the bonding networks in GeO2. Thus, the suppression of Ge-atom emission during the oxidation process leads to improved electrical properties of the Ge/GeO2 interfaces.