@misc{KaoScheweAkhtaretal., author = {Kao, Ming-Chao and Schewe, Lukas Paul and Akhtar, Arub and Rehm, Jana and Bin Anooz, Saud Bin and Galazka, Zbigniew and Popp, Andreas and Flege, Jan Ingo and Vonk, Vedran and Stierle, Andreas}, title = {Structure and Stability of Al-alloyed β-Ga2O3(100) surfaces}, series = {Verhandlungen der DPG, Berlin 2024}, journal = {Verhandlungen der DPG, Berlin 2024}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {β-Ga2O3 (GaO) holds great promise in high-power applications. GaO is predicted to outperform the leading technologies based on SiC and GaN due to a three times higher calculated critical field strength. It has been identified that alloying with Al results in an almost linear increase in the bandgap between Ga2O3 (4.85eV) and Al2O3 (7eV). A critical issue in the bandgap engineering of GaO is maintaining reasonable electron mobility, which is low for the pure material (150cm2/V/S). This project aims to explore GaO by Al alloying, which allows tunable wide bandgaps for engineering material properties and at the same time maintains excellent crystal quality. PXRD and their Rietveld refinement on several AlGaO crystals indicate a preferential ordering of Al and Ga over octahedral and tetrahedral sites. The results of an SXRD study using synchrotron radiation addressing the surface structure of β-AlxGa2-xO3(100) substrates with x=0-0.25. Our results indicate that the GaO(100) surface is nearly bulk terminated and remains smooth up to 800°C and 10-5mbar of molecular oxygen.}, language = {en} } @misc{KaoScheweAkhtaretal., author = {Kao, Ming-Chao and Schewe, Lukas Paul and Akhtar, Arub and Vlad, Alina and Keller, Thomas F. and Henkel, Karsten and Anooz, Saud Bin and Popp, Andreas and Galazka, Zbigniew and Flege, Jan Ingo and Stierle, Andreas and Vonk, Vedran}, title = {Surface termination of β-Ga₂O₃(100) as-cleaved single crystals}, series = {Applied physics letters}, volume = {128}, journal = {Applied physics letters}, number = {7}, publisher = {AIP Publishing}, address = {Melville, NY}, issn = {0003-6951}, doi = {10.1063/5.0309937}, pages = {1 -- 5}, abstract = {The surface of β-Ga₂O₃ single crystals cleaved along their (100) plane is investigated using surface x-ray diffraction and atomic force microscopy. The results show the surface to consist of a single, so-called B-termination, which means that the crystal cleaves at planes formed by edge-sharing oxygen octahedra, thereby breaking the longest and weakest Ga-O bonds. Refinement of the atomic positions results in small displacements from the bulk structure, at most approximately 0.01 {\AA}. Atomic force microscopy suggests that relatively large terraces form together with steps of half the a-axis length of approximately 0.6 nm, which means that terraces have the same atomic termination, related by the crystal symmetry. These results are important as a fundamental property of β-Ga₂O₃ when processed or used in various semiconductor applications.}, language = {en} }