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Point defects are at the heart of the important properties of wide band-gap and oxide semiconductors for power electronics applications, and therefore understanding the details of point defects and their role in determining the properties becomes imperative. Beta-Ga2O3 has received significant attention recently due to its unique advantages, including high breakdown voltage and availability as bulk substrates, which make it a viable candidate for next-generation power device applications. Here we present the first direct microscopic observation of the formation of interstitial-divacancy complexes within beta-Ga2O3 lattice using atomic resolution scanning transmission electron microscopy. We directly observed that cation atoms are present in multiple interstitial sites, and each interstitial atom is paired with two adjacent vacancies. The observed structure of the complexes is consistent with the calculation using density functional theory (DFT), which predicts them to be compensating acceptors. The number of the observed complexes increase as a function of Sn doping concentration, which matches with the increase in the concentration of the trap state at Ec - 2.1 eV measured using deep level optical spectroscopy, which strongly suggests that the defects corresponds to that trap level. Our finding provides new crucial information on the exact origin of the properties of beta-Ga2O3 that has been unobtainable using other methods. The results also provide new important insight on the material’s unique response to the impurity incorporation that can impact their properties, which can ultimately guide the development of growth and doping of new-generation materials for power electronics.
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