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Ferroelectricity is demonstrated for the first time in Si(100)/SiO2/TiN/HfO2-ZrO2/TiN stack using pulsed laser deposition (PLD) and the effects of temperatures, partial oxygen pressures, and thickness for the stabilization of the ferroelectric phase were mapped. Thin films deposited at a higher temperature and a higher oxygen partial pressure have a higher thickness, demonstrating a better ferroelectric response with ~12 µC/cm² remnant polarization, a leakage current of 10-7 A (at 8 V) and endurance >1011 cycles indicative of an orthorhombic crystal phase. In contrast, thin films deposited at lower temperatures and pressures does not exhibit ferroelectric behavior. These films can be attributed to having a dominant monoclinic phase, having lower grain size and increased leakage current. Finally, the effects of ZrO2 as top and bottom layer were also investigated which showed that ZrO2 as the top layer provided better mechanical confinement for stabilizing the orthorhombic phase instead of as the bottom layer. [ABSTRACT FROM AUTHOR]

(Ga1−xFex)2O3 thin films were grown on (0001)-Al2O3 substrates with a partial O2 pressure of 1.5 × 10–6 torr and temperature of 700°C by pulsed laser deposition. The incorporation of Fe into Ga2O3 expands the lattice constant and causes a transformation from the monoclinic phase to gamma phase for x ≥ 0.10, confirmed by X-ray diffraction and transmission electron microscopy. Surface analysis shows that Fe is also responsible for controlling the grains and the migration of adatoms with the increasing Fe concentration. Optical transmission measurements show that with increasing Fe content, the absorption edge moves toward longer wavelengths with no intermediate absorption. [ABSTRACT FROM AUTHOR]

Thin film wide bandgap Ga2O3 based alloys are important for applications in high power electronic, gate dielectric, deep UV photonics, spintronics and nuclear detectors. Epitaxial (Ga1−xGdx)2O3 thin films with varied x were successfully grown on Al2O3 (0001) substrates to tune the materials properties using variations in the growth parameters. High growth temperatures favor the formation of the monoclinic β- ( Ga1−xGdx)2O3 phase; the higher the Gd composition, the greater the growth temperature required for high quality crystalline thin films. Incorporation of Gd into Ga2O3 crystal expands the crystal lattice causing peak shift toward lower angle. UV–vis measurements demonstrate a slight red shift of the bandgap (4.99–4.82 eV) in comparison with the pure β-Ga2O3. Extracted refractive index from surface ellipsometry were in the range of 1.86–1.92. XPS spectroscopy confirmed the presence of Gd3+ oxidation states. Current voltage measurements demonstrate Gd doping increases the resistivity of the samples. Finally, our findings are confirmed by density functional study. [ABSTRACT FROM AUTHOR]