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Topological Amorphization of VO <sub>2</sub> via Chemical Locking for Durable Aqueous Zinc‐Ion Storage
ABSTRACT Although vanadium‐based oxides are promising cathodes for aqueous zinc‐ion batteries (AZIBs), their rigid crystalline lattices suffer from sluggish ion diffusion and rapid capacity decay caused by vanadium dissolution. Here, we report an organic‐driven topological amorphization strategy to construct a resilient and kinetically accelerated cathode. Using levamisole hydrochloride (LMS) as a dual‐functional modulator, strong Lewis's acid‐base interactions (V─N/V─S coordination) generate localized tensile stress that progressively disrupts the long‐range periodic lattice. This targeted lattice cleavage transforms crystalline VO 2 into a short‐range ordered amorphous sponge (denoted as L‐VO 2 ‐0.1), while preserving nanoclustered motifs interconnected through flexible organic “hinges”. The resulting topological architecture simultaneously reconciles the stability‐kinetics trade‐off, where the isotropic 3D open framework enables fast, sterically unimpeded Zn 2+ transport with capacitor‐like kinetics, while the dynamic organic hinges efficiently accommodate volume strain and thermodynamically suppress vanadium dissolution. Consequently, the L‐VO 2 ‐0.1 cathode delivers 481.6 mAh g −1 at 0.5 A g −1 and sustains 12 000 cycles at an extreme rate of 20 A g −1 with 83.5% capacity retention. Furthermore, a dual‐cathode pouch cell achieves a commercial‐grade absolute capacity of 1.15 Ah and a high areal capacity of 7.9 mAh cm −2 under a stringent mass loading (>20 mg cm −2 ), enabling feasible routes toward scalable, durable energy storage devices.
Helically Chiral Tetradentate Pt(II) Complexes for Simultaneous Deep‐Blue Electroluminescence and Circularly Polarized Luminescence via Diastereoselective Synthesis
ABSTRACT Circularly polarized organic light‐emitting diodes (CP‐OLEDs) have attracted great attention because of their promising applications in 3D displays. However, developing high‐performance CP‐OLEDs typically face the challenge of integrating large‐scale availability of emitters, device efficiency, color purity, and brightness, especially in the deep‐blue spectral region. Herein, we developed a novel strategy to successfully realize the diastereoselective and gram‐scale synthesis of helically chiral tetradentate Pt(II) complexes with high configurational stabilities through a central chirality adaptively induced helical chirality (CAIH) approach. The bulky central chiral moiety facilitates the suppression of intermolecular interactions and increases the color purity and molecular rigidity. R,M ‐PtCam2 showed a quantum efficiency of 99% and high color purity, with a full‐width at half‐maximum (FWHM) of 19.8 nm. R,M ‐PtCam2/ P ‐PtCam2‐based deep‐blue OLEDs successfully displayed obvious and mirror‐image CP electroluminescence signals. R,M ‐PtCam2 CP‐OLED exhibited a high color purity (FWHM = 24 nm) and a high maximum brightness of up to 51592 cd/m 2 ; moreover, it also achieved a maximum external quantum efficiency (EQE) of 33.2%, along with a record‐high EQE of 30.9% at 1000 cd/m 2 for all reported deep‐blue CP‐OLEDs with CIE y < 0.20. This study provides a molecular design strategy to prepare robust helically chiral Pt(II) emitters for high‐performance deep‐blue phosphorescent CP‐OLEDs.
Interfacial Dynamic Oxygen Exchange Preserves C─O Bonds for Selective CO <sub>2</sub> ‐to‐Ethanol Electrosynthesis
ABSTRACT Intermediate‐valence copper (Cu + ) is essential for preserving C─O bonds during the electrochemical reduction of CO 2 to ethanol, yet its progressive over‐reduction to Cu 0 under operating potentials inevitably dictates C─O bond cleavage and shifts selectivity toward ethylene. Herein, we propose an interfacial dynamic oxygen exchange strategy to stabilize Cu + sites and steer the ethanol reaction pathway. We realize this mechanism by engineering a few‐layer ceria‐coated cuprous oxide (Cu 2 O@CeO 2 ) catalyst featuring an oxygen vacancy‐rich heterointerface (Ce−O V −Cu). Operando spectroscopic measurements and density functional theory calculations reveal that these interfacial oxygen vacancies act as core mediators; by continuously capturing and migrating oxygen species derived from CO 2 , they effectively arrest the reduction of adjacent Cu + siteversuss. Crucially, this dynamic interface dictates the asymmetric C─C coupling of *CH 2 and *CHO, successfully preserving the C−O bond during the subsequent protonation of *CH 2 CHO to *CH 3 CHO. Consequently, the optimized catalyst delivers an outstanding ethanol Faradaic efficiency of 68.5% at −1.1 V versus RHE and exhibits robust operational stability exceeding 150 h, substantially outperforming pristine Cu 2 O. This study establishes vacancy‐mediated dynamic oxygen exchange as a robust strategy for preserving key oxygen‐containing functional groups in highly selective CO 2 ‐to‐ethanol electrosynthesis.
Conformational Elasticity at the Buried Interface: 26.89% Perovskite Solar Cells and 23.95% Certified Modules
ABSTRACT Conventional self‐assembled monolayers (SAMs) are conformationally rigid. They cannot buffer interfacial strain during rapid perovskite crystallization, limiting both film quality and device stability. We introduce a conformational engineering strategy using 2‐benzhydrylidene‐succinic acid (BSA), a rigid diphenylmethylene anchor with flexible succinic acid chains to create an elastic buried interface. Atomic simulations show BSA acts as a compressible buffer, delaying stress accumulation by ∼6 Å under displacement. This dynamic strain dissipation improves heterojunction contact and enhances hole extraction and transport. BSA‐modified p‐i‐n devices reach 26.89% (0.045 cm 2 , certified 26.52%). Large‐area modules (22.95 cm 2 ) deliver 24.30% (certified 23.95%), which is among the highest certified values for this area. The devices retain 90% of initial efficiency after 316 h of diurnal cycling and 88% after 300 extreme transient thermal shock cycles from ‐20 °C to 100 °C. This conformational design integrates mechanical compliance with electronic functionality in scalable perovskite photovoltaics.
Highly Tunable Schottky Barrier to 2D Semiconductors Enabled by an Inorganic‐Molecular‐Crystal Tunneling Layer
ABSTRACT Effective tuning of the Schottky barrier, which determines charge transport across the metal‐semiconductor interface, is essential for optimizing the performance of electronics and optoelectronic devices. However, interfacial disorders and orbital overlap between metals and semiconductors induce Fermi‐level pinning (FLP), making the Schottky barrier height (SBH) largely insensitive to metal work function. Here, we demonstrate that depositing an ultrathin inorganic molecular crystal layer of Sb 2 O 3 between metal and 2D semiconductors can eliminate FLP, enabling highly tunable SBH modulation. Owing to its van der Waals structure, Sb 2 O 3 introduces no excess defects and protects the fragile 2D channel from metal deposition damage, yielding a clean, defect‐free interface. Incorporation of Sb 2 O 3 tunneling layer significantly reduces the SBH in 2D MoS 2 transistors, and the polarity of 2D WSe 2 ‐based FET can be switched from n‐type to p ‐type via adjusting the contact metal work function. The pinning factor turns from −0.11 to around −0.93, approaching the ideal Mott‐Schottky limit. This scalable strategy offers broad applicability in high‐performance 2D electronics.
Intermediate‐Phase‐Mediated Homogeneous Crystallization of Wide‐Bandgap Perovskite for Efficient Silicon/Perovskite Tandem Solar Cells
ABSTRACT Achieving compositionally homogeneous mixed‐halide (I − and Br − ) wide‐bandgap (WBG) perovskite films is crucial for high‐performance perovskite/crystalline silicon tandem solar cells (TSCs), yet the disparate crystallization kinetics of iodide‐ and bromide‐rich phases readily induce halide segregation and inhomogeneous elemental distribution, thereby compromising the performance of TSCs. Herein, we employ 3,4,5‐trifluorobenzeneboronic acid (3FBBA) as a multifunctional modulator that synergistically interacts with both organic cations and lead‐halide octahedra via complementary hydrogen‐bonding and coordination interactions, by which 3FBBA fundamentally modulates the formation mechanism of α ‐phase perovskite. It transforms the spontaneous, uncontrolled direct crystallization pathway into a well‐regulated phase‐transition process mediated by highly ordered intermediate phases. These well‐structured intermediates act as well‐defined pre‐structural frameworks to guide the formation of high‐quality α ‐phase perovskite. Benefiting from this strategy, the resultant WBG perovskite films possess enlarged grain size and reduced defect density, which suppress nonradiative recombination loss and accelerate charge transfer kinetics. As a consequence, a single‐junction 1.66 eV WBG perovskite solar cell (PSC) achieves a high‐power conversion efficiency (PCE) of 24.09%, while a two‐terminal perovskite/silicon TSC delivers a champion PCE of 33.6%. Notably, the unencapsulated TSC maintains over 90% of its initial PCE throughout 571 h of continuous maximum power point tracking (MPPT) under ambient atmospheric conditions.
Causality analysis of vacuum chamber facility effects for Hall effect thruster operation
Characterization of plasma dynamics is critical for controlling electric propulsion systems on spacecraft. Understanding the causal relations between measurement data can play an important role both in minimizing the number of diagnostics and in informing which dynamic information needs to be accounted for in a computational model. In this paper, we apply extended convergent cross mapping (eCCM) to three measured telemetry signals—cathode current, discharge voltage, and cathode-to-ground voltage—collected from a krypton-fed magnetically shielded Hall-effect thruster with base operating pressures of 6.8 and 8.5 μTorr at the 4.5 and 6 kW power levels, respectively. Data were also collected at elevated pressures, two to three times the base operating pressure. We discuss the sensitivity of the cross-mapping skill to the embedding parameters and background pressure in the vacuum chamber. We propose eCCM as a framework for characterizing dynamic relationships in the Hall-effect thruster circuit, guiding the selection of signals and the prioritization of dynamic measurements in subsequent physics-based modeling and diagnostic efforts. The results show that cross-mapping skill decreases across nearly all signal pairs for both power levels, indicating a reduction in mutual dynamic information between electrical circuit components as background pressure increases. The analysis suggests that the discharge plasma is coupled to other unmeasured components in the system as the facility pressure varies.
Polaron-induced efficiency limitations of solar H2O splitting by BiVO4
In this paper, we present a theoretical study of atomistic mechanisms of polaron formation in BiVO4 and its impact on solar-to-hydrogen (STH) conversion efficiency. We simulated polaron formation, calculated the energies of polaron states, and computed the frequency-dependent dielectric function using first-principles density functional theory and density functional perturbation theory, both with the Hubbard U correction. The results indicate the formation of electron polarons at vanadium sites and hole polarons at oxygen sites. The calculated energies of polaronic states result in the values of photovoltage of ∼0.53 and ∼1.16 eV for electron and hole polarons, respectively. These photovoltage results are not only lower than the estimated optical gap of 2.40 eV but also smaller than the minimum potential energy required for water splitting (2.00 eV), indicating that polaron formation limits the photovoltage. Furthermore, the computed dielectric function revealed changes in both the optical and static dielectric constants due to polaron formation. These changes correlate closely with the total dielectric constant, which influences the effective potential well as well as the maximum polaron binding energy and, consequently, the polaron mobility.
Suppression of Curie temperature through severe shear strain in lanthanum manganite LaMnO3+ <i>δ</i>
The effects of severe shear stress on the electron-transfer-induced ferromagnetism of lanthanum manganite LaMnO3+δ have been investigated. Shear stress was applied via high-pressure torsion (HPT) processing and controlled by varying the number of rotations N. A decrease of 30 K in the Curie temperature TC was observed under shear strain, in contrast to hydrostatic compression, which increases TC. Examination of the x-ray diffraction patterns revealed an increase in the unit-cell volume, indicating negative pressure. A correlation between the decrease in TC and the increase in lattice parameter a was observed. A decrease in the valence state of Mn after HPT processing was also confirmed via x-ray photoelectron spectroscopy. Thereby, the valence change, as well as defect insertion and lattice strain, weakens the double-exchange interaction. This underscores the potential of shear strain as a platform for tuning electron-transfer-induced ferromagnetism and for strain engineering in LaMnO3+δ.
Morphological confinement of secondary phases in entropy stabilized oxides
Four transition metal entropy-stabilized oxide samples were synthesized with varying processing methods to create four different average grain sizes: 90 nm, 200 nm, 430 nm, and 15 μm. All samples were heat treated to form a Cu-rich tenorite secondary phase, analyzed by scanning electron microscopy and energy-dispersive x-ray spectroscopy. Three secondary-phase morphologies were identified: Cu-rich tenorite needle-like particles, Cu-rich tenorite filled grain boundaries, and Cu-rich tenorite nano-grains. Average grain size and boundary layer thickness have a significant impact on the morphology of the secondary phase. The effect of grain size and boundary layer thickness on the secondary-phase morphology, termed morphological confinement, was simulated using Dream 3.D with a tetrakaidekahedron geometric model. These synthetic microstructure simulation results produced three confinement regimes (unconfined particles, confined particles, and morphological confinement). For coarse-grain samples, the geometric conditions allow for unconfined secondary-phase particles to form in the primary phase. For nanocrystalline grain samples, the geometric conditions restrict the secondary-phase formation to individual nanograins, distinct from primary-phase nanograins. For intermediate grain sizes, there is a diffuse transition between the morphological confinement regimes, allowing a sample to exhibit one or more secondary-phase morphologies simultaneously. Consequently, this study highlights the novel approach of using grain size to manipulate the morphology of secondary phases in multi-phase ceramics, establishing the foundation for future studies on the effect of the morphology variation on functional and mechanical behavior.
Achieving ultra-low surface roughness on aluminum alloys via picosecond laser milling–polishing
Producing high-quality milled surfaces on metals, particularly aluminum alloys, using laser-based techniques remains a considerable processing challenge, especially when ultra-low surface roughness is required. In this study, a novel laser milling–polishing (LMP) process employing a 1064 nm picosecond laser is proposed by integrating laser milling and laser polishing into a single processing strategy. Under optimized conditions with a laser fluence of 45.69 J/cm2 and 425 scanning passes, the surface roughness of the aluminum alloy is significantly reduced from 1.33 μm for the untreated surface to 90 nm after LMP treatment. Surface characterization indicates an increase in the oxygen content together with enhanced microhardness after laser treatment, indicating significant modification of the near-surface layer. Based on the observed evolution of the surface morphology, composition, and mechanical properties, a plausible mechanism for ultra-smooth surface formation is proposed. The results suggest that progressive reduction in effective energy density during multi-pass scanning induces a transition from ablation-dominated removal to shallow micro-melting and rapid resolidification, promoting material redistribution and surface leveling. The proposed LMP approach, therefore, provides an effective route toward high-precision laser finishing of aluminum alloys and other thermally sensitive metals.
Field-tunable acoustic damping in FeGaB/AlScN shear-mode solidly mounted resonators
We theoretically investigate field-tunable acoustic damping in a FeGaB/tilted-AlScN/Mo thickness-shear solidly mounted resonator (SMR) using a coupled transfer-matrix and Landau–Lifshitz–Gilbert (TMM-LLG) model. The field- and frequency-dependent complex elastic stiffness of FeGaB is incorporated into the multilayer transfer matrix to calculate electrical impedance, series quality factor Qs, and effective electromechanical coupling keff2. A three-pair Mo/SiO2 Bragg reflector confines acoustic energy, while a 15° c-axis-tilted AlScN layer excites a pronounced shear mode near 1.69 GHz. Under perpendicular DC magnetic bias, acoustically driven ferromagnetic resonance (ADFMR) enables resonant phonon–magnon energy transfer and strongly reduces Qs. The resulting Q-factor modulation yields a maximum calculated sensitivity SQ ≈ 1400 T−1 at Ha ≈ 0.13 T and an estimated limit of detection (LoD) of 71.4 μT for ΔQmin = 0.1. Despite strong magneto–acoustic attenuation, keff2 remains above 3.69%, indicating sustained piezoelectric transduction. The contribution of this work is the device-level implementation of ADFMR-induced Qs modulation in a thickness-shear SMR, rather than a new magneto–acoustic mechanism. The required static bias is an external system-level requirement. The LoD is model-based and should not be interpreted as an experimentally validated noise floor or state-of-the-art detection limit.
Abrupt amplification of self-excited acoustic oscillations in a thermoacoustic engine with non-zero mean flow
In this study, we conducted experiments on a quarter-wavelength standing-wave thermoacoustic engine (TAE) and unexpectedly observed self-excited acoustic oscillations even when the left end was partially closed (with a central orifice connected to a tube). Remarkably, when suction was applied to the tube, the acoustic oscillations exhibited a sudden increase followed by gradual attenuation. Motivated by these phenomenological observations, we systematically explored the influence of control parameters including flow rates, lengths, and outlet distance of suction tubes on the performance of the TAE. Results reveal that nonlinear effects play a significant role in the abrupt amplification of acoustic oscillations (while the stack temperature difference increases by less than 1%) in the presence of a non-zero mean flow. There are optimal values of control parameters at which the thermoacoustic amplification is maximized. Under optimal conditions, the maximum pressure amplitude increased by a factor of 2.8. This study has successfully demonstrated the feasibility of using a non-zero mean flow to amplify acoustic oscillations in TAEs, offering great value in promoting the application of thermoacoustic technology in the fields of thermal power generation and energy harvesting.
Perspectives on magnetic/superconductor hybrid systems: Long-range electromagnetic phenomena induced by proximity effect and interfacial spin–orbit coupling
In this Perspective, we review recent achievements in physics and applications of hybrid superconductor–ferromagnet structures. In particular, we focus on the manifestations of the electromagnetic phenomena in these systems originating from the response of the induced superconducting correlations modified by the exchange field and additional effects coming from the interface Rashba-type spin–orbit coupling. The review includes the long-range electromagnetic proximity effect and related modification of magnetic textures, spontaneous currents, and properties of vortex matter and its interaction with magnetic ordering, spin-galvanic, photogalvanic, and nonreciprocal transport phenomena in exemplary hybrid systems. We also present our views on the future development of this field, including both the theoretical challenges and promising opportunities for fundamental experiments.
Demonstrating the accuracy of terahertz absorption spectroscopy and cavity ringdown spectroscopy by a comparison of atomic oxygen density measurements
This work presents a comparison of absolute ground-state atomic oxygen densities measured with terahertz (THz) absorption spectroscopy and cavity ringdown spectroscopy (CRDS). All measurements were performed on the same capacitively coupled radio frequency oxygen discharge, for applied powers in the range of 20–100 W and gas pressures of 70 and 130 Pa. When preconditioning of the reactor walls was taken into account to ensure reproducibility of the results, the atomic oxygen densities obtained with THz absorption spectroscopy and CRDS were found to be in excellent agreement. It can be concluded that both of these techniques can be reliably used to measure line-of-sight integrated atomic oxygen densities with high accuracy.
Second harmonic generation by lithium metasilicate grains in photocrystallized glass
The present work explores the formation of lithium metasilicate (Li2SiO3) crystalline grains in a photosensitive glass similar to Foturan® and the nonlinear optical characteristics displayed by the formed composite material. For partial crystallization of the glass, we applied the conventional three-step procedure: UV irradiation, primary heat treatment, and secondary annealing at higher temperature. The formation of crystalline Li2SiO3 was confirmed by Raman spectroscopy. The specimens exhibit quadratic optical nonlinearity without poling. The measured patterns of second optical harmonic radiation of the fabricated specimens demonstrate a two-lobe shape, characteristic of μm-sized second harmonic sources. Simulations in accordance with the nonlinear Rayleigh–Gans–Debye scattering model allowed us to estimate the average grain sizes: ∼1.0 μm after 20 min of secondary anneal, ∼2.7 μm after 40 min, and ∼4.7 μm after 60 min. The UV exposure duration shows a weak influence on the grain size. The combination of photolithography defining UV-irradiated regions with annealing-controlled crystallite size appears to be a promising approach for the fabrication of multi-element structures capable of generating second harmonics with a desired radiation pattern.
Viscosity estimation from elastohydrodynamic response of a magnetic flagellated microswimmer
Reliable viscosity measurement at small length scales is essential for a wide range of applications, from microfluidics to biomedical systems. The magnetic flagellated microswimmers, whose dynamics arise from the coupled effects of elasticity, hydrodynamics, and magnetic actuation, offer a promising route to estimate viscosity. In this study, we propose a multiparametric approach to exploit the dynamics of a microswimmer for sensing the fluid viscosity. A finite-element-based model of a flagellated microswimmer is developed and analyzed to identify the characteristic parameters. The extracted time- and frequency-domain descriptors are found to be highly sensitive to variations in fluid viscosity. Machine learning models are subsequently developed to capture the relationship between these extracted features and fluid viscosity, resulting in strong predictive performance and reliable estimation of viscosity. The findings of this study reveal a previously unrecognized perspective, wherein the amplitudes of harmonic components (f, 2f, 4f) among the extracted features serve as dominant indicators for accurate viscosity estimation. The validity of the proposed approach is further confirmed by a scaled-up experimental system with a millimeter-sized swimmer under low Reynolds number conditions. The experimental observations retain the underlying physical behavior and substantiate the relevance of the extracted features, with the amplitudes of harmonic components playing a pivotal role in viscosity prediction. The agreement between numerical and experimental results highlights the potential of this framework as a reliable and scalable strategy for viscosity sensing, offering a promising alternative to conventional viscosity measurement techniques.
Topological spectral features and tight-binding Hamiltonian in the thermal noise of transmission-line networks
We investigate topological features of Johnson–Nyquist noise in networks of coaxial transmission lines. These networks exhibit well-known topological effects, such as bandgaps and protected edge states. In contrast to other topolectrical circuit systems, the transmission-line networks analyzed herein are intrinsically excited, and since constituent elements are comparable in size to the resonant wavelength, the Hamiltonian formalism is motivated by these distinctions. The noise spectrum can be predicted by a Hamiltonian analogous to that of electrons in a tight-binding model, and a newly introduced variable characterizes the symmetry of each mode and predicts its frequency and width. Certain networks sustain a dark mode that cannot be externally detected or excited, but whose presence is nonetheless guaranteed by the fluctuation–dissipation theorem. When the geometrical uniformity of the network is slightly broken, this previously invisible mode appears at the frequency predicted by the Hamiltonian. Transmission-line networks represent a promising platform for studies of topological physics since the resonant frequency, coupling strength, and connectivity can be easily modified. Owing to chiral symmetry, these eigenmodes are topologically protected in the face of small perturbations arising from component imperfections and intentional symmetry breaking.
Role of amorphous phase in phase transformation of nanograined NiTi alloy: Insights from molecular dynamics simulations
This study employs molecular dynamics simulations to investigate how amorphous layer thickness affects martensitic transformation in homogeneous and gradient nanograined (NG and GNG) NiTi shape memory alloys (SMAs). Amorphous-homogeneous nanograined and amorphous-gradient nanograined models are constructed to examine temperature- and stress-induced transformations, as well as loading-direction dependence. With increasing amorphous layer thickness, the onset temperature of temperature-induced transformation decreases and the transformation rate weakens. In GNG NiTi, transformation primarily occurs in large-grain regions, where low-temperature shear strain localizes. For stress-induced transformation, thicker amorphous layers lead to higher critical stress, peak stress, Young's modulus, energy dissipation, and residual strain, but lower martensite content. After unloading, residual shear strain concentrates at grain boundaries and amorphous regions. Under different loading directions, martensite variant types vary within the same grain, and the tensile transformation plateau is longer than the compressive one. Increased amorphous layer thickness reduces the critical and peak stress ratios between compression and tension, narrows the transformation region, and alleviates tension–compression asymmetry. The difference in martensite content between tension and compression is small in GNG alloys but large in NG alloys. Dislocation density under compression is significantly higher than under tension and decreases with amorphous layer thickness. In GNG NiTi, dislocations mainly distribute in large-grain regions. This atomic-scale study reveals the microscopic mechanism by which amorphous layer thickness regulates martensitic transformation and mechanical response, offering a theoretical basis for designing high-performance SMAs with low asymmetry.
Impact of strain-induced cracking on the electrical performance of pseudo-vertical GaN-on-Si p–n diodes grown by selective area epitaxy
Selective-area growth (SAG) of gallium nitride (GaN)-on-silicon enables the growth of thick layers by elastically relaxing tensile stress during cooldown. However, the effects of strain-induced mechanical degradation on the performance of SAG-grown vertical devices remain poorly understood. In this work, pseudo-vertical GaN-on-Si p–n diodes were made by SAG on 200 mm Si (111) wafers to study how mesa geometry and drift-layer thickness affect performance. Devices with 9 μm-thick drift layers showed a strong dependence of specific on-resistance (Ron,sp) on mesa diameter, with 100 μm mesas showing lower Ron,sp than 200 μm ones. Structural analysis revealed greater degradation in mesa performance due to strain-induced cracking and delamination at the mesa base, disrupting conduction between the anode and the n+-GaN layer. Reducing the drift-layer thickness to 4 μm suppressed cracks and improved Ron,sp consistency. Devices without a p-GaN layer had even lower Ron,sp, indicating that the p-GaN layer and contact dominate resistance once cracks are mitigated. These findings highlight mechanical integrity as a key factor in the performance and uniformity of SAG-grown pseudo-vertical GaN-on-Si power devices.