A5032380139- Ga2O3 and related materials
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Leibniz Institute for Crystal Growth
2021-2025
Deutschen Konsortium für Translationale Krebsforschung
2022
Technische Universität Dresden
2022
We have systematically studied the growth, by Czochralski method, and basic physical properties of a 2 cm in. diameter bulk β-(AlxGa1−x)2O3 single crystal with [Al] = 0–35 mol. % in melt 5 steps. The segregation coefficient Al Ga2O3 1.1–1.2 results higher content crystals than melt. were also co-doped Si or Mg. 30 (33–36 crystals) seems to be limit for obtaining high structural quality suitable homoepitaxy. either semiconducting (no intentional co-dopants 0–30 Si-doped 15–20 %), degenerately...
This work investigated the metalorganic vapor-phase epitaxy (MOVPE) of (100) β-Ga2O3 films with aim meeting requirements to act as drift layers for high-power electronic devices. A height-adjustable showerhead achieving a close distance susceptor (1.5 cm) was demonstrated be critical factor in increasing stability Ga wetting layer (or adlayer) on surface and reducing parasitic particles. film thickness up 3 μm has been achieved while keeping root mean square below 0.7 nm. Record carrier...
The morphology evolution of (1 0 0) β-Ga2O3 films grown by metalorganic vapor phase epitaxy (MOVPE) is studied atomic force microscopy (AFM). In particular, when under a high O2/Ga ratio (O2/Ga = 1250) and above thickness 350 nm, these exhibit striking morphological instabilities, including step meandering bunching, which contribute significantly to surface roughening. Transmission electronic (TEM) measurements reveal transition on the growing with coexistence step-flow step-bunching growth...
Absrtract In this work, we comprehensively investigate the development of unwanted parasitic particles in MOVPE chamber while growing μ m level films. The density is found to be pronounced at film thicknesses starting from >1.5 2 m. These seem induce structural defects such as twin lamellae, thereby harming electrical properties grown film. origin particle attributed reactions within triggered by promoted gas-phase during growth process, which can largely reduced increasing total gas flow...
This study focuses on the impact of high-doping impurities (>1018 cm−3) morphology homoepitaxially grown (100) 4° off β-Ga2O3 film, as well incorporating insights from Cabrera–Vermilyea model (C–V model). Using atomic force microscopy imaging, we reveal that under low-supersaturation conditions, dopant-induced lead to irregular step formation and growth stalling, inducing step-bunching consistent with C–V predictions. Conversely, higher supersaturation conditions restore desired...
Abstract With comprehensive crystal growth experiments of β‐(Al x Ga 1‐x ) 2 O 3 by the Czochralski method this work concludes a maximum [Al] = 40 mol% (35 in melt) that can be incorporated into β‐Ga lattice while keeping single crystalline and monoclinic phase, resulting formula 0.4 0.6 . Transmission Electron Microscopy (TEM) analysis reveals random distribution Al across both octahedral tetrahedral sites. This has shown, incorporation only [Ga] ≥ 5 α‐Al crystals leads to phase separation...
A Langmuir adsorption model of the Si incorporation mechanism into metalorganic vapor-phase epitaxy grown (100) β-Ga2O3 thin films is proposed in terms competitive surface process between and Ga atoms. The outcome can describe major feature doping indicate a growth rate-dependent behavior, which validated experimentally further generalized to different conditions substrate orientations.
In this work, we explored the growth regime of (100) β-Ga2O3 homoepitaxial films on substrates with different miscut angles (1°, 2°, and 4°) in MOVPE system. Under a low O2/Ga ratio condition, step-flow can be maintained up to 3 μm angles. Moreover, results reveal that rate decreases slightly decreasing angles, which matches estimation Burton–Cabrera–Frank theory explained by model adsorption–desorption. By comparing miscut-dependent rates, give experimental evidence fundamental difference...
In this work, we analyze the optimum annealing conditions for activation of Ge-implanted β-Ga2O3 in order to reach low ohmic contact resistances. The experiments involved use a pulsed rapid thermal treatment at temperatures between 900 and 1200 °C nitrogen atmosphere. Our investigations show remarkable changes surface morphology involving increased roughness after high-temperature above 1000 as well significant redistribution implanted Ge. Nevertheless, specific resistance is strongly...
Metalorganic vapor-phase epitaxy of β-Ga2O3/c-plane Al2O3 heterostructures was monitored in-situ by spectral reflectance in different wavelengths. The spectrum analysed as a function the growth time and incident wavelength to estimate rate refractive index at temperatures. obtained values are validated ex-situ methods such secondary ion mass measurement spectroscopic ellipsometry. A theoretical simulation carried out combining transfer matrix method with multilayer model, good agreement...
In this work, we train a hybrid deep-learning model (fDNN, Forest Deep Neural Network) to predict the doping level measured from Hall Effect measurement at room temperature and investigate behavior of Si dopant in both (100) (010) β-Ga2O3 thin film grown by metalorganic vapor phase epitaxy (MOVPE). The reveals that hidden parameter, supplied per nm (mol/nm), has dominant influence on process compared with other parameters. An empirical relation is concluded estimate (mol/nm) as primary...
Beta gallium oxide (β-Ga2O3) is a promising ultra-wide bandgap semiconductor with attractive physical properties for next-generation high-power devices, radio frequency electronics, and solar-blind ultraviolet radiation detectors. Here, we present an overview perspective on the development of MOVPE-grown (100) β-Ga2O3 thin films its role in supplementing electronics. We review path growth process discussion regarding solved remaining challenges. The structural defect formation mechanism,...
<title>Abstract</title> This study explores the transfer of optimized growth conditions from (100) to (010) orientation in β-Ga<sub>2</sub>O<sub>3</sub> films via metalorganic vapor phase epitaxy (MOVPE) process, aiming uncover a shared window. While demands intentional substrate treatment for ideal growth, requires specific lower surface roughness. Our findings reveal that low O<sub>2</sub>/Ga flux ratio condition enables uniform process both orientations across various film thicknesses...
Accurate detection and segmentation of the intraprostatic gross tumor volume (GTV) is pivotal for radiotherapy (RT) in primary prostate cancer (PCa) since it influences focal therapy target volumes patients' cT stage. The study aimed to compare performance multiparametric resonance imaging (mpMRI) with [18F] PSMA-1007 positron emission tomography (PET) GTV as well delineation evaluate their respective influence on RT concepts. In total, 93 patients from two German University Hospitals...
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The anisotropic thermal conductivity and the phonon mean free path (mfp) in monoclinic $\beta$-Ga$_2$O$_3$ single crystals homoepitaxial films of several $\mu$m were determined using 3$\omega$-method temperature range from 10K-300 K. measured effective both, crystal are order 20 W/(mK) at room temperature, below 30 K it increases with a maximum 1000 to 2000 decreases T$^3$ 25 Analysis mfp shows dominance phonon-phonon-Umklapp scattering above 80 K, which influence point-defect is observed....
<title>Abstract</title> In this work, we report the out-diffusion and uphill-diffusion of Mg inside (100) β-Ga<sub>2</sub>O<sub>3</sub> epilayer substrate. The accumulates towards surface upon annealing under an oxidizing environment, whereas concentration profile changes with temperature time. Furthermore, from substrate into is observed at temperatures above 800 ℃, which continues during film growth. substitutional-interstitial-diffusion (SID) mechanism suggested to be driving for former,...
<title>Abstract</title> This study focuses on the impact of high-doping impurities (> 10<sup>18</sup> cm<sup>− 3</sup>) morphology homoepitaxially grown (100) 4°off β-Ga<sub>2</sub>O<sub>3</sub> film, as well incorporating insights from Cabrera-Vermilyea model (C-V model). Using atomic force microscopy (AFM) imaging, we reveal that under low supersaturation conditions, dopant-induced lead to irregular step formation and growth stalling, inducing step-bunching consistent with C-V...
Phonon-mediated heat conduction in high-purity crystals is governed by Fourier's law for diffusive transport and phonon-radiative transfer (PRT) between the surfaces ballistic transport. PRT characterized a phonon mean free path (mfp) that limited crystal size. The authors demonstrate here crossover from to transparent wide-band gap \ss{}-Ga${}_{2}$O${}_{3}$ MOCVD homoepitaxially grown layers on single substrates. Such phonon-transparent interfaces may be employed design flow future...
Abstract In this work, the out‐diffusion and uphill‐diffusion of Mg inside (100) β‐Ga 2 O 3 epilayers substrates are reported. The accumulates toward surface upon annealing under an oxidizing environment, whereas concentration profile changes with temperatures durations. Furthermore, from substrate into epilayer is observed at above 800 °C, which continues during film growth. substitutional‐interstitial‐diffusion (SID) mechanism suggested to be driving for former, latter related diffusion...
Metalorganic vapor-phase epitaxy of β-Ga2O3/c-plane Al2O3 heterostructures was monitored in-situ by spectral reflectance in different wavelengths. The spectrum analysed as a function the growth time and incident wavelength to estimate rate refractive index at temperatures. obtained values are validated ex-situ methods such secondary ion mass measurement spectroscopic ellipsometry. A theoretical simulation carried out combining transfer matrix method with multilayer model, good agreement...