High-dielectric constant and wide band gap inverse silver oxide phases of the ordered ternary alloys of SiO$_{2}$, GeO$_{2}$ and SnO$_{2}$

TL;DR

This study uses first-principles calculations to explore the structural, elastic, and electronic properties of inverse silver oxide phases of SiO₂, GeO₂, SnO₂, and their ternary alloys, revealing stable wide band gap, high dielectric materials compatible with silicon.

Contribution

It provides a comprehensive first-principles analysis of the stability and electronic properties of inverse silver oxide phases and ternary alloys of SiO₂, GeO₂, and SnO₂, highlighting their potential for technological applications.

Findings

GeO₂ and SnO₂ have negative phonon branches indicating instability.

Ternary alloys are stable with dielectric constants between 10 and 20.

Computed GW band gaps confirm wide band gap and high dielectric properties.

Abstract

High-dielectric constant and wide band gap oxides have important technological applications. The crystalline oxide polymorphs having lattice constant compatibility to silicon are particularly desirable. One recently reported candidate is the inverse silver oxide phase of SiO$_2$. First-principles study of this system together with its isovalent equivalents GeO$_{2}$, SnO$_{2}$ as well as their ternary alloys are performed. Within the framework of density functional theory both generalized gradient approximation and local density approximation (LDA) are employed to obtain their structural properties, elastic constants and the electronic band structures. To check the stability of these materials, phonon dispersion curves are computed which indicate that GeO$_{2}$ and SnO$_{2}$ have negative phonon branches whereas their ternary alloys Si$_{0.5}$Ge$_{0.5}$O$_{2}$, Si$_{0.5}$Sn$_{0.5}$O$_{2}$, and Ge$_{0.5}$Sn$_{0.5}$O$_{2}$ are all stable within LDA possessing dielectric constants ranging between 10 to 20. Furthermore, the lattice constant of Si$_{0.5}$Ge$_{0.5}$O$_{2}$ is virtually identical to the Si(100) surface. The $GW$ band gaps of the stable materials are computed which restore the wide band gap values in addition to their high dielectric constants.