Ga Diffusion Research Articles

Impact of Channel Thickness and Doping Concentration for Normally-Off Operation in Sn-Doped β-Ga2O3 Phototransistors.

We demonstrate a Sn-doped monoclinic gallium oxide (β-Ga2O3)-based deep ultraviolet (DUV) phototransistor with high area coverage and manufacturing efficiency. The threshold voltage (VT) switches between negative and positive depending on the β-Ga2O3 channel thickness and doping concentration. Channel depletion and Ga diffusion during manufacturing significantly influence device characteristics, as validated through computer-aided design (TCAD) simulations, which agree with the experimental results. We achieved enhancement-mode (e-mode) operation in <10 nm-thick channels, enabling a zero VG to achieve a low dark current (1.84 pA) in a fully depleted equilibrium. Quantum confinement in thin β-Ga2O3 layers enhances UV detection (down to 210 nm) by widening the band gap. Compared with bulk materials, dimensionally constrained optical absorption reduces electron-phonon interactions and phonon scattering, leading to faster optical responses. Decreasing β-Ga2O3 channel thickness reduces VT and VG, enhancing power efficiency, dark current, and the photo-to-dark current ratio under dark and illuminated conditions. These results can guide the fabrication of tailored Ga2O3-based DUV phototransistors.

Diffusion of Co and Ga in α-Ti

The diffusion of Co and Ga atoms in α-Ti has been studied using the projector augmented-wave method in combination with the transition state theory. The formation energies of the interstitial and substitutional defects and the corresponding migration and activation energies along two crystallographic directions within the interstitial and vacancy diffusion mechanisms have been calculated. It has been shown that the energetically preferred interstice for the incorporation of both impurities is crowdion. In the case of Co, the formation energy of this defect is only 0.7 eV higher than that of the substitutional defect, while for Ga this difference reaches 2.6 eV. Using the Landman method and the eight-frequency model, the diffusion coefficients of Co and Ga have been calculated within both interstitial and vacancy mechanisms. It has been shown that Co diffusion occurs faster through the interstitials, while Ga diffuses within the vacancy mechanism. The migration and activation energies as well as diffusion coefficients and their anisotropy obtained in these cases are consistent with experimental data.

Shifting the Paradigm: A Functional Hole‐Selective Transport Layer for Chalcopyrite Solar Cells

High‐efficiency Cu(In,Ga)Se2 solar cells rely on Ga grading to mitigate back surface recombination. However, the inhomogeneous absorber has drawbacks, including increased non‐radiative loss and inadequate absorption. Therefore, literatures demand a paradigm shift of using a hole‐transport layer to passivate the back surface. Herein, a functional hole‐transport layer is demonstrated as an alternative to Ga grading. The novel hole‐transport layer is prepared as a double‐layer: co‐evaporated CuGaSe2 covered by solution combustion synthesis prepared In2O3. As demonstrated by micrographs, elemental mapping, and photoluminescence spectroscopy, the oxide layer improves thermal stability and prevents Ga diffusion. However, during the absorber deposition, a complete ion exchange of In and Ga converts CuGaSe2/In2O3 into CuInSe2/GaOx. Incorporating this hole‐transport layer in co‐evaporated nongraded CuInSe2 solar cells leads to significantly increased minority carrier lifetime from 5 to 113 ns, yielding an 80 meV improvement in quasi‐Fermi‐level splitting. The devices exhibit improved open‐circuit voltage, as well as a promising fill factor of over 71%, indicating good hole‐transport properties. In these results, the passivation effect and good hole‐transport properties of the hole‐transport layer are experimentally demonstrated. Thus, high‐efficiency solar cells can be achieved by using a functional hole‐transport layer without relying on Ga grading.

A novel thermal annealing process to improve Ga diffusion in CIGS thin film solar cells

A novel thermal annealing process to improve Ga diffusion in CIGS thin film solar cells

High‐Temperature Annealing of Si‐Doped AlGaN

This study explores the impact of Si doping on the material properties of high‐temperature annealed (HTA) Al0.71Ga0.29N layers, which are grown on AlN/sapphire templates. The AlGaN layers are doped with Si by applying different IV/III ratios during epitaxial growth and compared to undoped Al0.71Ga0.29N. Before HTA, the threading dislocation density (TDD) for all samples is about 6.0 × 109 cm−2. After HTA, the Si‐doped AlGaN grown with the highest IV/III ratio of 3.6 × 104 shows the lowest TDD of 1.2 × 109 cm−2. Secondary ion mass spectrometry depth profiles reveal an accelerated Ga diffusion from the doped AlGaN into the AlN buffer layer compared to undoped AlGaN. This suggests that the Ga diffusion process is mediated by Si diffusion. Consequently, the Ga diffusion leads to a decrease in the Ga mole fraction of annealed Si‐doped AlGaN. Furthermore, strain relaxation is higher for the Si‐doped AlGaN than for the undoped AlGaN, before and after HTA. The results from this study suggest that Si doping can be a new promising approach in enhancing the quality of HTA‐AlGaN as a useful template for the growth of UV LED heterostructures.

Effects of low-temperature annealing on net doping profile of Mg-ion-implanted GaN studied by MOS capacitance–voltage measurement

Effects of long-term low-temperature cap annealing on the net doping profile of Mg-ion-implanted GaN were studied using MOS structures before activation annealing. Mg ions were lightly implanted into n-type GaN to maintain the n-type conduction. Various cap-layer materials, i.e. Al2O3, SiN, SiO2 and capless, for low-temperature annealing were examined. Doping profiles were derived from capacitance–voltage (C–V) curves. Before 600 °C annealing, negatively charged defects were distributed on the shallower side of the detection depth range, whereas positively charged defects existed on the deeper side. Upon 600 °C annealing, however, the doping profile changed toward a flat shape regardless of the cap-layer material used during annealing. The observed profile change was likely caused by the diffusion of defects. Detailed analyses of C–V characteristics showed that the highly likely cause of the observed phenomena is the diffusion of Ga and N interstitials.

Sb-saturated high-temperature growth of extended, self-catalyzed GaAsSb nanowires on silicon with high quality

Ternary GaAsSb nanowires (NW) are key materials for integrated high-speed photonic applications on silicon (Si), where homogeneous, high aspect-ratio dimensions and high-quality properties for controlled absorption, mode confinement and waveguiding are much desired. Here, we demonstrate a unique high-temperature (high-T >650 °C) molecular beam epitaxial (MBE) approach to realize self-catalyzed GaAsSb NWs site-selectively on Si with high aspect-ratio and non-tapered morphologies under antimony (Sb)-saturated conditions. While hitherto reported low-moderate temperature growth processes result in early growth termination and inhomogeneous morphologies, the non-tapered nature of NWs under high-T growth is independent of the supply rates of relevant growth species. Analysis of dedicated Ga-flux and growth time series, allows us to pinpoint the microscopic mechanisms responsible for the elimination of tapering, namely concurrent vapor–solid, step-flow growth along NW side-facets enabled by enhanced Ga diffusion under the high-T growth. Performing growth in an Sb-saturated regime, leads to high Sb-content in VLS-GaAsSb NW close to 30% that is independent of Ga-flux. This independence enables multi-step growth via sequentially increased Ga-flux to realize uniform and very long (>7 μm) GaAsSb NWs. The excellent properties of these NWs are confirmed by a completely phase-pure, twin-free zincblende (ZB) crystal structure, a homogeneous Sb-content along the VLS-GaAsSb NW growth axis, along with remarkably narrow, single-peak low-temperature photoluminescence linewidth (<15 meV) at wavelengths of ∼1100–1200 nm.

Palladium-Based Contacts on p-GaN and Their Application in Laser Diodes.

In this paper, we investigate the effect of Pd thickness and heat treatment on Pd/Ni/Au/p-GaN metal contacts. The as-deposited samples exhibit a smooth morphology and non-linear I-V characteristics. Heat treatment in a N2 atmosphere leads to degradation of the contact microstructure, resulting in diffusion of Ga, void formation on the interface and mixing of metals. Annealing in a mixture of N2 and O2 improves adhesion and reduces contact resistance. However, this process also induces GaN decomposition and species mixing. The mixing of metal-Ga and metal-metal remains unaffected by the method of thermal treatment but depends on gas composition for thin Pd contacts. To achieve low-resistance contacts (≈1 × 10-4 Ω cm2), we found that increasing the Pd thickness and using N2 + O2 as the annealing environment are effective measures. Nevertheless, the degradation effect of the annealed contact microstructure in the form of the void generation becomes evident as the thickness of Pd increases. Laser diodes (LDs) with optimized palladium-based contacts operate at a voltage of 4.1 V and a current density of 3.3 kA/cm².

Atomistic models of In and Ga diffusion in Cu(In,Ga)Se2

To improve the performance of Cu(In,Ga)Se2 thin-film photovoltaic devices, a robust understanding of the dominant diffusion pathways of the alloy species In and Ga is needed. Here, the most probable defect complexes and mechanisms for In and Ga diffusion are identified with the aid of density functional theory. The binding energies and migration barriers for these complexes are calculated in bulk CuInSe2 and CuGaSe2. Analytic models and kinetic lattice Monte Carlo simulations are employed to predict the diffusivity of In and Ga under variations in composition and temperature. We find that a model based on coulombic interactions between group III antisites and vacancies on the Cu-sublattice produces results that match well with experiment.

Ion Diffusion Management Enables All-Interface Defect Passivation of Perovskite Solar Cells.

Perovskite solar cells (PSCs) have demonstrated over 25% power conversion efficiency (PCE) via efficient surface passivation. Unfortunately, state-of-the-art perovskite post-treatment strategies can solely heal the top interface defects. Herein, we propose an ion diffusion management strategy to concurrently modulate the top interfaces, buried interfaces, and bulk interfaces (i.e., grain boundaries) of perovskite film, enabling all-interface defect passivation. Specifically, this method is enabled by applying double interactive salts of octylammonium iodide (OAI) and guanidinium chloride (GACl) onto the three-dimensional (3D) perovskite surface. We reveal that the hydrogen-bonding interaction between OA+ and GA+ decelerates the OA+ diffusion and therefore forms dimensionally broadened 2D capping layer. Additionally, the diffusion of GA+ and Cl- determines the composition of the bulk and buried interface of PSCs. As a result, we can obtain n-inter-i-inter-p, i.e., 5-layer structured PSCs with a champion PCE of 25.43% (certified 24.4%). This approach also enables the substantially improved operational stability of perovskite solar cells. This article is protected by copyright. All rights reserved.

Electrical and Structural Analysis of β‐Ga2O3/GaN Wafer‐Bonded Heterojunctions with a ZnO Interlayer

AbstractWafer bonding of β‐Ga2O3 and N‐polar GaN single crystal substrates is demonstrated by adding ZnO as a “glue” interlayer. The wafers are fully bonded such that Newton rings are not observed. Temperature‐dependent current‐voltage (I–V) measurements are conducted on the as‐bonded Ga2O3/ZnO/N‐polar GaN test structure and after annealing at 600 °C and 1100 °C. The impact of post‐annealing temperature on the electrical and structural characteristics of the bonded samples is investigated. A consistently ohmic‐like characteristic is obtained by annealing the bonded wafers at 1100 °C in N2, which is in part due to crystallization of ZnO and diffusion of Ga into ZnO which makes it n‐type doped. The wafer bonding of β‐Ga2O3 and GaN achieved in this work is promising to combine the material merits of both GaN and Ga2O3 targeting breakthrough high‐frequency and high‐power device performances.

The Heteroepitaxy of Thick β-Ga2O3 Film on Sapphire Substrate with a β-(AlxGa1-x)2O3 Intermediate Buffer Layer.

A high aluminum (Al) content β-(AlxGa1-x)2O3 film was synthesized on c-plane sapphire substrate using the gallium (Ga) diffusion method. The obtained β-(AlxGa1-x)2O3 film had an average thickness of 750 nm and a surface roughness of 2.10 nm. Secondary ion mass spectrometry results indicated the homogenous distribution of Al components in the film. The Al compositions in the β-(AlxGa1-x)2O3 film, as estimated by X-ray diffraction, were close to those estimated by X-ray photoelectron spectroscopy, at ~62% and ~61.5%, respectively. The bandgap of the β-(AlxGa1-x)2O3 film, extracted from the O 1s core-level spectra, was approximately 6.0 ± 0.1 eV. After synthesizing the β-(AlxGa1-x)2O3 film, a thick β-Ga2O3 film was further deposited on sapphire substrate using carbothermal reduction and halide vapor phase epitaxy. The β-Ga2O3 thick film, grown on a sapphire substrate with a β-(AlxGa1-x)2O3 buffer layer, exhibited improved crystal orientation along the (-201) plane. Moreover, the scanning electron microscopy revealed that the surface quality of the β-Ga2O3 thick film on sapphire substrate with a β-(AlxGa1-x)2O3 intermediate buffer layer was significantly improved, with an obvious transition from grain island-like morphology to 2D continuous growth, and a reduction in surface roughness to less than 10 nm.

Interfacial reactions between liquid Ga and solid Au

• Interfacial reactions between liquid Ga and solid Au were investigated. • Only one intermetallic phase, AuGa 2 , was formed from room temperature to 150 °C. • Time exponents for the AuGa 2 growth were determined to be 0.91–2.01. • Grain boundary diffusion of Ga was assumed to be the rate-determining step for AuGa 2 growth. Interfacial reactions between liquid Ga and solid Au were investigated from room temperature to 150 °C. It was found that only one intermetallic phase, AuGa 2 , was formed at the Ga/Au interface at all temperatures. During storage, the newly formed fresh AuGa 2 phase continuously nucleated and grown at room temperature on the preformed AuGa 2 /Au interface under supercooled liquid Ga. Time exponents for the AuGa 2 growth were measured to be 0.91–1.44 and 2.01 at room temperature to 125 °C and 150 °C, respectively, with an activation energy of 85.4 kJ/mol at 100–150 °C. Diffusion of Ga atoms through the AuGa 2 grain boundaries was assumed to be the rate-determining step for AuGa 2 growth.

High Thermoelectric Performance in Polycrystalline GeSiSn Ternary Alloy Thin Films.

Group IV materials are promising candidates for highly reliable and human-friendly thin-film thermoelectric generators, used for micro-energy harvesting. In this study, we investigated the synthesis and thermoelectric applications of a Ge-based ternary alloy thin film, Ge1-x-ySixSny. The solid-phase crystallization of the highly densified amorphous precursors allowed the formation of high-quality polycrystalline Ge1-x-ySixSny layers on an insulating substrate. The small compositions of Si and Sn in Ge1-x-ySixSny (x < 0.15 and y < 0.05) lowered the thermal conductivity (3.1 W m-1 K-1) owing to the alloy scattering of phonons, while maintaining a high carrier mobility (approximately 200 cm2 V-1 s-1). The solid-phase diffusion of Ga and P allowed us to control the carrier concentration to the order of 1019 cm-3 for holes and 1018 cm-3 for electrons. For both p- and n-type Ge1-x-ySixSny, the power factor peaked at x = 0.06 and y = 0.02, reaching 1160 μW m-1 K-2 for p-type and 2040 μW m-1 K-2 for n-type. The resulting dimensionless figure of merits (0.12 for p-type and 0.20 for n-type) are higher than those of most environmentally friendly thermoelectric thin films. These results indicate that group IV alloys are promising candidates for high-performance, reliable thin-film thermoelectric generators.

Quantifying the Structure and Chemistry of Semiconductor Devices with the Latest Advancements in Scanning Transmission Electron Microscopy

Electron microscopy has been revolutionized by the advent of the aberration corrector and advances in detector both for imaging and spectroscopy. Aberration correction dramatically improved spatial resolution into the sub-ångstrom regime, while new detectors have unlocked information about materials that was previously only imaginable.While these recent advances have proven essential to the atomic scale characterization of materials, many measurements have remained largely semi-quantitative. In particular, accuracy and precision for scanning transmission electron microscopy (STEM) was significantly hampered by the presence of sample drift and scan distortion. Until recently, this limitation has obscured the capabilities to characterize minute changes to the atomic structure that can ultimately define material properties.In this talk, we will introduce revolving scanning transmission electron microscopy (RevSTEM) for the characterization of semiconductors. The method uses a series of fast-acquisition STEM images, but with the scan coordinates rotated between successive frames. This scan rotation introduces a concomitant change in image distortion that is then used to analyze the sample drift rate and direction. Multiple case studies will be presented to demonstrate the power of this technique to characterize electronic materials. For example, we will show how picometer level precision and accuracy enabled the capability to directly quantify ferroelectric HfO2 thin films. We will also show how RevSTEM images can be used to accurately determine crystallographic parameters in real-space, and to determine the structural origins of polarization.When combined with modern spectroscopy tools, the technique can directly inform growth mechanisms in AlN based materials for fabrication of quantum well structures. Specifically, We will show the interface quality between various AlGaN/AlN quantum wells using a combination of high-angle annular dark-field (HAADF) imaging and energy dispersive X-ray spectroscopy (EDS). We will show that we can directly measure the lattice parameters for each layer and how they vary across each AlN/AlGaN interface. Using EDS, we correlate the lattice parameters and lattice parameter values to the chemical composition in each layer. We show that throughout multiple quantum well structures, there is an asymmetrical interface with a diffusion of Ga on one side of the AlGaN layer. Further, we will discuss fluctuation in the composition present throughout each layer and the role on the local strain distribution.

Nanoscale Characterization of Chemical and Structural Properties of the Au/(100) β-Ga2O3 Interface

Au/β-Ga2O3 Schottky contacts deposited at room temperature via electron-beam evaporation are characterized electrically with current density–voltage (J–V) and capacitance–voltage (C–V) measurements. The ideality factor and Schottky barrier heights measured from J–V and C–V are determined to be 1.32, 1.37 eV, and 1.98 eV, respectively. Due to the peculiarities of the electrical properties of the Au/β-Ga2O3 Schottky contacts, scanning transmission electron microscopy (STEM) was performed. High-angle annular dark-field (HAADF)-STEM imaging reveals an inhomogeneous chemical reaction occurred at the metal–semiconductor interface. The reaction is signified by void formation 5–20 nm below the interface, Ga diffusion into Au at the interface, and Ga interstitial diffusion toward the interface. Energy-dispersive X-ray spectroscopy (EDS) mapping shows Ga diffusion into the Au contact region accompanied by a transitional region of 4–5 nm.

(Invited) ALD HfO2/β-Ga2O3 Reliability for Future Power Devices

The ultra-wide bandgap (UWBG) semiconductor, β-gallium oxide, has shown great potential in power devices due to its excellent electrical properties and availability of high-quality single-crystalline substrates. Significant progress has been made in the development of β-Ga2O3 metal-oxide-semiconductor (MOS) devices, but further progress will require optimization of the gate-dielectric interface. In this talk, I will describe the investigation of HfO2 dielectric reliability on β-Ga2O3 for future power devices. I fabricated β-Ga2O3 (010) MOS capacitors with atomic layer deposited (ALD) HfO2 and used capacitance-voltage (C-V) and current density-voltage (J-V) techniques to analyze the electrical reliability of ALD HfO2/β-Ga2O3 MOSCAPs. Positive bias stress measurements indicated that HfO2/β-Ga2O3 MOSCAPs are more susceptible to charge trapping at lower electric stress fields compared to HfO2/Si MOSCAPs, likely due to the smaller conduction band offset between HfO2 and β-Ga2O3. Initial flatband voltage shifts were observed for C-V sweeps of HfO2/β-Ga2O3 MOSCAPs, showing the significance of border traps within the dielectric. The lack of mobile holes in the β-Ga2O3 impedes the recombination of these trapped charges in the dielectric while the MOSCAP is in depletion. We observed full recovery from stress-induced charge trapping in the HfO2/β-Ga2O3 MOSCAPs upon deep ultra-violet illumination. The negative valence band offset between the dielectric and semiconductor allows the recombination of photo-generated holes with the trapped dielectric charges [1]. Because many fabrication steps require high temperature processing, we also investigated the thermal reliability of the ALD HfO2/β-Ga2O3 (010) interface. Negligible Ga atom diffusion was observed in secondary ion mass spectrometry (SIMS) depth profiles for anneals at temperatures up to 850°C in N2 environment for 10 minutes. Significant Ga diffusion into the HfO2 layer was observed upon annealing at 900°C, resulting in a severely degraded MOS structure. Additional analysis was performed to investigate the impact of high temperature processing on the MOS electrical characteristics [2].H.N.M was supported by a National Science Foundation Graduate Research Fellowship under Grant No. DGE 1256260. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. Portions of this work were performed at the Lurie Nanofabrication Facility and J. D. Hanawalt X-Ray MicroAnalysis Laboratory, which are supported by the College of Engineering at the University of Michigan.[1] H. N. Masten, J. D. Phillips, and R. L. Peterson, “Charge trapping and recovery in ALD HfO2/β-Ga2O3 (010) MOS capacitors,” Semicond. Sci. Technol., vol. 36, no. 4, p. 04LT01, Mar. 2021, doi:10.1088/1361-6641/abe880.[2] H. N. Masten, J. D. Phillips, and R. L. Peterson, “Effects of High Temperature Annealing on the Atomic Layer Deposited HfO2 /β-Ga2O3 (010) interface,” Journal of Applied Physics, Accepted.

Formation and Effect of Deposited Thin TiO2 Layer With Compressive Strain and Oxygen Vacancies on GaAs (001) Substrate

The integration of metal oxides and GaAs semiconductors is quite attractive for its potential applications, but interfacial diffusion and lattice mismatch usually cause huge challenges toward achieving high-performance electronic devices. In this article, we reported a thin layer of epitaxial TiO2 (110) on a GaAs (001) substrate with significant compressive strain, lattice distortion, and oxygen vacancies, where the oxygen vacancies proved to be the critical factor to induce the compressive strain and lattice distortion. In this case, the lattice mismatches between this compressed TiO2 (110) and GaAs (001) surface were calculated to be as small as 1.3 and 0.24% along the [110] and [001] orientations of TiO2, respectively. Further, no Ga-oxides or As-oxides were found at the interface, indicating that the TiO2 layer inhibited the diffusion of Ga and As atoms effectively. In summary, TiO2 film can be grown epitaxially on GaAs (001) substrates with non-negligible compressive strain, lattice distortion, oxygen vacancies, and a high-quality interface. This study also provides an approach to integrate different functional oxides on TiO2-buffered GaAs for various GaAs-based electronic devices with higher reliability and performance.

Recrystallization behavior, oxygen vacancy and photoluminescence performance of sputter-deposited Ga2O3 films via high-vacuum in situ annealing

Ga 2 O 3 films were deposited on Si substrates through radio-frequency magnetron sputtering at room temperature and were annealed in situ in a high-vacuum environment. The as-deposited Ga 2 O 3 film exhibited an island-like surface morphology and had an amorphous microstructure, with a few nanocrystalline grains embedded in it. After high-temperature in situ annealing, the films recrystallized and exhibited coalesced surfaces. Because of the thermally driven diffusion of Ga, the interfacial layer between Si and Ga 2 O 3 was composed of SiGaO x . Compared with ex situ annealing in air, in situ annealing in high vacuum is more advantageous because it enhances surface mobility and improves the crystallinity of the Ga 2 O 3 films. The higher oxygen vacancy concentration of in situ annealed films revealed that oxygen atoms were easily released from the Ga 2 O 3 lattice during high-vacuum annealing. Photoluminescence (PL) spectra exhibited four emission peaks centered in ultraviolet, blue, and green regions, and the peak intensities were significantly enhanced by thermal annealing at >600 °C. This work elucidates the effect of the in situ annealing treatment on the recrystallization behavior, interfacial microstructure, oxygen vacancy concentration, and PL performance of the Ga 2 O 3 films, making it significant and instructional for the further development of Ga 2 O 3 -based devices.

Effects of high temperature annealing on the atomic layer deposited HfO2/β-Ga2O3(010) interface

Atomic layer deposited HfO2 is a primary candidate for metal–oxide–semiconductor (MOS) power devices based on the ultra-wide bandgap semiconductor β-Ga2O3. Here, we investigated the thermal stability of this stack. Out-diffusion of gallium into HfO2, measured by secondary ion mass spectroscopy depth profile, was observed after annealing at 900 °C. Electrical characterization of MOS capacitors (MOSCAPs) showed that this diffusion caused a dramatic increase in leakage current. For annealing temperatures between 700 and 850 °C, no significant Ga diffusion into the HfO2 layer was observed. Nonetheless, MOSCAPs made with stacks annealed at 700 °C have significantly higher forward bias leakage compared to as-prepared MOSCAPs. Through photo-assisted capacitance–voltage measurements (C–V), we found that this leakage is due to an increase in interface traps (Dit) lying 0.3–0.9 eV below the conduction band. We thus have identified how thermal treatments influence HfO2/Ga2O3 behavior: for anneals at 700–850 °C, we observe an increase in Dit and leakage, while annealing at &amp;gt;900 °C results in notable Ga out-diffusion and a catastrophic degradation in leakage. This understanding is key to improving the performance and reliability of future β-Ga2O3 MOS power devices.