A5041483979- Ga2O3 and related materials
- Advanced Photocatalysis Techniques
- ZnO doping and properties
- Magnesium Oxide Properties and Applications
Carnegie Mellon University
2022-2024
Nominally phase-pure γ-Ga2O3 was deposited on (100) MgAl2O4 within a narrow temperature window centered at ∼470 °C using metal-organic chemical vapor deposition. The film 440 exhibited either poor crystallization or an amorphous structure; the grown 500 contained both β-Ga2O3 and γ-Ga2O3. A nominally obtained 530 °C. Atomic-resolution scanning transmission electron microscopy (STEM) investigations of 470 revealed high density antiphase boundaries. planar defect model developed for γ-Al2O3...
Phase transitions in metastable α-, κ(ε)-, and γ-Ga2O3 films to thermodynamically stable β-Ga2O3 during annealing air, N2, vacuum have been systematically investigated via situ high-temperature x-ray diffraction (HT-XRD) scanning electron microscopy (SEM). These respective polymorphs exhibited thermal stability ∼471–525 °C, ∼773–825 ∼490–575 °C before transforming into β-Ga2O3, across all tested ambient conditions. Particular crystallographic orientation relationships were observed after the...
Phase and microstructural evolution of gallium oxide (Ga2O3) films grown on vicinal (0001) sapphire substrates was investigated using a suite analytical tools. High-resolution transmission electron microscopy scanning film at 530 °C revealed the initial pseudomorphic growth three to four monolayers α-Ga2O3, 20–60 nm transition layer that contained both β- γ-Ga2O3, top ∼700 nm-thick phase-pure κ-Ga2O3. Explanations for occurrence these phases their sequence formation are presented. Additional...
Ga2O3 films were deposited on (100) MgAl2O4 spinel substrates at 550, 650, 750, and 850 °C using metal-organic chemical vapor deposition investigated x-ray diffraction transmission electron microscopy. A phase-pure γ-Ga2O3-based material having an inverse structure was formed °C; a mixture of the γ-phase β-Ga2O3 detected in grown 750 °C. Only determined 650 550 β- to transition occurred from substrate/film interface during growth The stabilization outset film affected by substantial Mg Al...
Atomic resolution scanning/transmission electron microscopy (S/TEM) and energy-dispersive x-ray (EDX) analysis were used to determine the effects of annealing at 800–1000 °C in air on Ga2O3 films grown (100) MgAl2O4 650 via metal-organic chemical vapor deposition. Annealing resulted diffusion Mg Al into concomitantly with transformation β-Ga2O3 γ-Ga2O3 solid solutions. The minimum atomic percent + that corresponded was ∼4.6 at. %. Analyses atomic-scale STEM images EDX profiles revealed atoms...
κ-Ga2O3 has been predicted to be a potential ferroelectric material. In this work, undoped Ga2O3 films were grown by either plasma-enhanced atomic layer deposition (PEALD) or metal organic chemical vapor (MOCVD) on platinized sapphire substrates. 50 nm thick PEALD with mixture of and β-Ga2O3 had relative permittivity ∼27, loss tangent below 2%, high electrical resistivity up ∼1.5 MV/cm. 700 MOCVD predominantly the phase permittivities ∼18 1% at 10 kHz. Neither film showed compelling evidence...
Gallium oxide (Ga 2 O 3 ) is an ultra-wide band gap semiconductor with extraordinary potential for high-power, high-frequency, and high-temperature electronics UV optoelectronics. The existence of stable metastable phases, or polymorphs, Ga presents challenges opportunities future device development. β-Ga the thermodynamically phase occurs in melt-grown, single-crystal substrates. which have been demonstrated pure- mixed-phase form epitaxial films, also possess bandgaps. Intriguing...