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AlN thin films, grown on (0001) sapphire substrates by molecular beam epitaxy (MBE), were annealed at high temperature (up to 1650 °C) in flowing N2. X-ray diffraction (XRD) studies, combined with Williamson-Hall and Srikant plots, have shown that annealing leads to a strong reduction of both edge and mixed threading dislocation densities, as...
In this work, ammonia source molecular beam epitaxy is explored as an alternative technique to grow ScAlN/GaN High Electron Mobility Transistor heterostructures. The effect of growth temperature and ScAlN barrier thickness on 2dimensional electron gas density is investigated with capacitancevoltage measurements. A transistor with a maximum...
The microstructure of nonpolar heteroepitaxial wurtzite films (GaN and ZnO-based) is dominated by the presence of planar basal stacking faults (BSFs). In this paper, transmission electron microscopy studies of both GaN and ZnO nonpolar films oriented either (11–20) or (1–100) and grown on sapphire substrates, permit to propose and evaluate...
The in-plane polarities of GaN and ZnO non-polar films deposited on r - and m-sapphire are compared. The polarity is unique on r-sapphire and mixed on m-sapphire because the direction on the substrate surface parallel to the wurztite c-direction is polar in the first case and nonpolar in the second case. Furthermore, on r-sapphire where GaN and...
The hetero-epitaxial growth of Fe3O4 thin films on ZnO is studied in the context of opto-spintronic applications, paying a thorough attention to the interface optimization. The samples are grown by pulsed laser deposition using either Fe2O3 or Fe3O4 targets. Firstly, we establish the Fe3O4 growth windows at various oxygen partial pressures and...
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