Unraveling the Growth Dynamics of Rutile Sn<sub>1-<i>x</i></sub>Ge<sub><i>x</i></sub>O<sub>2</sub> Using Theory and Experiment.
basic_science · Level V
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- Record sourced from PubMed, PMID 39729044.
- Also identified by DOI 10.1021/acs.nanolett.4c05043.
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Abstract
Rutile GeO<sub>2</sub> and related materials are attracting interest due to their ultrawide band gaps and potential for ambipolar doping in high-power electronic applications. This study examines the growth of rutile Sn<sub>1-<i>x</i></sub>Ge<sub><i>x</i></sub>O<sub>2</sub> films through oxygen-plasma-assisted hybrid molecular beam epitaxy (hMBE). The film composition and thickness are evaluated across a range of growth conditions, with the outcomes rationalized by using density functional theory calculations. We find that up to 34% Ge can be successfully incorporated into Sn<sub>1-<i>x</i></sub>Ge<sub><i>x</i></sub>O<sub>2</sub>/r-Al<sub>2</sub>O<sub>3</sub> (<i>x</i> ≤ 0.34) at 600 °C. Our phase diagram calculations suggest that spinodal decomposition occurs at Ge concentrations exceeding 34%. However, the formation of a Ge-rich rutile phase is inhibited by amorphization of the Ge-rich film and volatility of GeO. We therefore speculate that maximizing the Ge content requires higher Ge flux and more oxidizing environments, providing insights into the growth mechanism of Sn<sub>1-<i>x</i></sub>Ge<sub><i>x</i></sub>O<sub>2</sub> and paving the way toward the synthesis of pure rutile GeO<sub>2</sub> films.