Understanding the growth of rutile Ge oxides in hybrid MBE

Nanostructured oxide materials hold significant promise for advanced electronic and sensing applications due to their tunable electronic properties. Rutile GeO₂ is one such material that has garnered attention for its ultrawide band gap and potential in high-power electronics. However, challenges in synthesizing high-quality thin films hinder the exploration of its intrinsic properties. In this talk, I will present the growth of Sn_1-xGe_xO₂ films through oxygen-plasma-assisted hybrid molecular beam epitaxy (hMBE) using metal-organic precursors. We examine how composition, temperature, and precursor flux influence film quality and phase formation, with insights guided by density functional theory (DFT) calculations. Our findings show that up to 34% Ge can be incorporated into Sn_1-xGe_xO₂, beyond which spinodal decomposition leads to amorphization and Ge volatility. Vapor pressure calculations based on DFT-fit regular solution models indicate that optimizing temperature and oxygen partial pressure is essential to control volatility while ensuring sufficient kinetics for film crystallization. These results demonstrate how ab-initio thermodynamic calculations can be leveraged to understand the growth of multi-component oxide materials.