On the structural and bandgap properties of mist-CVD-grown κ-Ga2O3 post continuous temperature annealing
Source abstract
Abstract
We investigate the continuous annealing of orthorhombic κ-Ga2O3 films on AlN/c-plane sapphire templates grown by Mist Chemical Vapor Deposition (mist-CVD) using in situ high-temperature x-ray diffraction (HT-XRD). Increasing the annealing temperature from 400 to 1100 °C in both vacuum and ambient air reveals a phase transition onset at 825 °C. High-resolution transmission electron microscopy and XRD demonstrated that annealing within the stability window of 650 to 775 °C effectively improves the crystal quality of the κ-Ga2O3 thin film. Optical transmittance and low-loss electron energy loss spectroscopy (EELS) show the pristine film’s bandgaps to be 4.96 and 4.67 eV, respectively, with reduced bandgaps in annealed films due to increased defect density. EELS-derived optical joint density of states indicates that air-annealing fosters sub-bandgap radiative processes, while vacuum annealing suppresses them, qualitatively correlated with the observed photoluminescence intensity variations. The results of this comprehensive high-temperature annealing study offer crucial insight into the influence of annealing ambient conditions on the crystallographic properties of κ-Ga2O3 films and the associated evolution of extended sub-bandgap states.
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Research context
OpenAlex topics: Ga2O3 and related materials · ZnO doping and properties · Advanced Photocatalysis Techniques
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Photonics Laboratory, Electrical and Computer Engineering, Division of Computer, Electrical and Mathematical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST) 1 , Thuwal 23955-6900,
Semiconductor Materials Center, Korea Institute of Ceramic Engineering and Technology (KICET) 2 , Jinju 52851,
Department of Materials Science and Engineering, Pusan National University 3 , Busan 46241,
Imaging and Characterization Core Lab, King Abdullah University of Science and Technology (KAUST) 4 , Thuwal 23955-6900,
Currently with Department of Physics, Khalifa University 5 , P.O. Box 127788, Abu Dhabi,
Sustainability and Photonics Energy Research Lab, Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST) 6 , Thuwal 23955-6900,
Department of Electrical and Computer Engineering, University of Wisconsin-Madison 7 , Madison, Wisconsin 53706,
Funding
King Abdullah University of Science and Technology
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