First-Principles Study for Evidence of Low Interface Defect Density at Ge/GeO$_2$ Interfaces

TL;DR

This study uses first-principles calculations to show that Ge/GeO₂ interfaces have lower defect densities than Si/SiO₂ interfaces, due to differences in bonding network flexibility, which improves electrical properties.

Contribution

It provides first-principles evidence that Ge/GeO₂ interfaces have inherently lower defect densities compared to Si/SiO₂ interfaces, explaining their superior electrical characteristics.

Findings

Ge/GeO₂ interfaces exhibit smaller energy advantages for atom emission than Si/SiO₂.

High flexibility of GeO₂ bonding networks reduces defect formation.

Lower defect density improves electrical properties of Ge/GeO₂ interfaces.

Abstract

We present the evidence of the low defect density at Ge/GeO$_2$ interfaces in terms of first-principles total energy calculations. The energy advantages of the atom emission from the Ge/GeO$_2$ interface to release the stress due to the lattice mismatch are compared with those from the Si/SiO$_2$ interface. The energy advantages of the Ge/GeO$_2$ are found to be smaller than those of the Si/SiO$_2$ because of the high flexibility of the bonding networks in GeO$_2$. Thus, the suppression of the Ge-atom emission during the oxidation process leads to the improved electrical properties of the Ge/GeO$_2$ interfaces.