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HL: Fachverband Halbleiterphysik

HL 38: Oxide Semiconductors II

HL 38.4: Vortrag

Donnerstag, 21. März 2024, 10:15–10:30, ER 325

Ultrawide Bandgap Semiconductor Cubic Spinel Zn₂GeO₄ Epitaxial Thin Films — •Jingjing Yu, Sijun Luo, and Marius Grundmann — Felix Bloch Institute for Solid State Physics, Faculty of Physics and Earth System Sciences, Universität Leipzig, 04103 Leipzig

It is significant to explore new ultrawide bandgap oxides thin films with a bandgap larger than 4 eV for potential applications in power electronics and deep-UV photodetectors. Cubic spinel Zn₂GeO₄ is a high-temperature and high-pressure metastable phase, to date, only the synthesis and crystal structure are reported. In this work, we report the heteroepitaxial growth of (100)-oriented cubic spinel Zn₂GeO₄ thin films on cubic spinel (100) MgAl₂O₄ single crystal substrates using pulsed laser deposition. The 350 nm thick (100) Zn₂GeO₄ epitaxial thin film shows a full width at half maximum of rocking curve of (800) reflex of about 0.35^∘. The direct optical bandgap is evaluated to be about 5 eV. The resistivity of film decreases gradually from about 4.0 to 0.5 Ω cm as temperature increases from 50 to 350 K. The Hall electron carrier mobility increases from 4.3 to 28.4 cm² V⁻¹s⁻¹ while the Hall electron carrier concentration slightly increases from about 3.5 x 10¹⁷ to about 4.6 x 10¹⁷ cm⁻³ as the temperature increases from 50 to 350 K. The n-type conductivity probably originates from oxygen vacancies-related defects, as the post annealing at high temperatures in the air could make the thin film become insulating. This work advances the fundamental research on ultrawide bandgap cubic spinel Zn₂GeO₄ semiconductor thin films for potential device application.

Keywords: ultrawide bandgap oxide semiconductor; epitaxial oxide thin film; pulsed laser deposition; electrical property