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Functional gradient materials (FGMs) possess gradient-varying properties, which make them important in applications for connecting different materials and inhomogeneous environments. Ferroelectric single crystals have multiple excellent physical properties, but it is difficult to design gradient properties during the crystal growth. Here, a method is reported to achieve gradient piezoelectric properties in the tetragonal Mn&Fe-doped KTa1−xNbxO3 (Mn&Fe: KTN) crystals by alternating current poling and internal strain design. Furthermore, opposite piezoelectric coefficients are obtained in the direction perpendicular to the applied electric field, with a gradient variation from −221 to 227 pC/N. This phenomenon has been revealed to result from the co-regulating effect of flexoelectric field and alternating current electric field on defect dipoles and domain structures. This study contributes to the fabrication of functional gradient piezoelectric single crystals and expands the application scenarios of FGMs. [ABSTRACT FROM AUTHOR]

Nonlinear optical process is a key technology to realize optical communication. Potassium tantalate niobate (KTa1−xNbxO3, KTN) crystals with large nonlinear optical coefficients are potential functional materials for realizing χ2 nonlinear optical processes. However, to accurately modulate the nonlinear optical signals of KTN crystals, the relationship between their second harmonic generation (SHG) properties and ferroelectric domain structures needs to be further investigated. Here, we report the special SHG processes generated by self-assembled structures in KTN crystals. Multimode quasi-phase matching and broadband nonlinear Bragg diffraction are achieved with the changing of polarizations and wavelengths of the fundamental wave. The physical processes behind the multi-polarization and multi-wavelength SHG properties of the KTN crystals are revealed. Our results about the multi-polarization and multi-wavelength SHG properties of KTN crystals will provide guidance for the design and realization of multimode nonlinear optical processes. [ABSTRACT FROM AUTHOR]

In this Letter, we present a p-GaN gate enhancement-mode GaN-on-Si high-electron mobility transistor fabricated using Mg-acceptor re-passivation realized through ammonia plasma treatment. The gate-to-source and gate-to-drain access regions of the device were treated with ammonia plasma using a plasma-enhanced chemical vapor deposition system, resulting in the formation of a high-resistivity GaN cap layer. The fabricated device has a high threshold voltage (VTH) of 2.0 V and a low gate reverse leakage current (IGR) of 10−11 A/mm. A breakdown voltage (BVOFF) of 670 V together with a specific on-resistance (Ron,sp) of 0.87 mΩ cm2 was obtained in a device with LGD = 6 μm. The measured dynamic on-resistance (Ron,d) at a quiescent drain voltage (Vds,q) of 600 V with a stress time of 10 and 120 s is 1.06 and 1.34 times of the static on-resistance (Ron,s), respectively. Good thermal stability of VTH and gate current IG were observed after a thermal stress at 175 °C for 100 h. The developed fabrication techniques exhibit a great potential to be applied into GaN power transistors. [ABSTRACT FROM AUTHOR]

Rare-earth titanate pyrochlores have attracted significant attention for their unique magnetic frustration; however, research on the origin of low-temperature dielectric dispersion and the relationship between dielectric properties and structure lags far behind. Here, by systematically investigating the dielectric properties of representative rare-earth titanates R2Ti2O7 (R = La, Nd, Sm, Er, Yb, and Lu), we demonstrate that R2Ti2O7 with a cubic pyrochlore structure exhibits low-temperature dielectric dispersion behavior, while the other compounds with a monoclinic perovskite-like layered structure possess no dispersion behavior but excellent temperature-stable dielectric property. The dielectric dispersion in cubic pyrochlores arises from the structural distortion. Furthermore, the existence of structural distortion is affirmed by the anomalous phonon softening of A1g Raman mode around the dielectric dispersion temperature, and the origin of the structural distortion is attributed to anharmonic phonon–phonon interactions induced by intrinsic vacant oxygen at Wyckoff 8a sites. In addition, with increasing ionic radius from R = Lu to Sm, the increased lattice parameter leads to varied bond length and bond angle of Ti-O(1)-Ti, which strengthens the local lattice distortion of TiO(1)6 octahedra and thus enhances diffusion degree of dielectric dispersion. On the other hand, the absence of intrinsic vacant oxygen site hardly gives rise to the local structural distortion and thus no dielectric dispersion in monoclinic R2Ti2O7. Our work not only clarifies the mechanism of dielectric dispersion but also gives a comprehensive perspective on the structure–property relationship of rare-earth titanates R2Ti2O7, and thus lays a solid foundation for further work on related materials. [ABSTRACT FROM AUTHOR]

Magnetic heterojunctions with large exchange bias have promising applications in magnetic sensing and data storage. Ferromagnetic/antiferromagnetic (FM/AFM) heterojunctions are often used to generate exchange bias. However, the requirement of thermal manipulation makes controlling exchange bias in FM/AFM heterojunctions inconvenient. Herein, a Fe3GeTe2/Fe3GaTe2 FM/FM heterojunction is constructed to generate large exchange bias and reflected magnetic circular dichroism and magneto-optical Kerr effect techniques are used for the magnetic characterization of the heterojunction. The results show that strong magnetic coupling occurs at the Fe3GeTe2/Fe3GaTe2 interface when the temperature is <80 K. By fixing the spin direction of Fe3GaTe2, large exchange bias can be generated in Fe3GeTe2 because of the magnetic pinning effect. Furthermore, the strength of exchange bias can be manipulated by applying an ultralow current between Fe3GeTe2 and Fe3GaTe2 layers without changing the temperature. These results provide potential ways for generating and manipulating exchange bias in two-dimensional (2D) materials and pave the way for implementing the 2D van der Waals exchange bias effect in spintronic devices. [ABSTRACT FROM AUTHOR]

Modern application trends for the development of RGB displays with a high color rendering index (CRI) require light-emitting diode (LED) display technology with greater miniaturization and efficient LEDs operating at deep red wavelengths greater than 650 nm. Although InGaN-based LEDs have achieved high miniaturization performance, efforts to obtain deep-red emission by increasing the indium content introduce a number of factors limiting optical performance, such as high in-plane stress, high dislocation densities, and phase separation. The present work addresses this issue by fabricating deep-red emitting InGaN-based LEDs on an underlying GaN template layer grown from hexagonal GaN column structures formed on a porous SiNx masking layer and coalesced in situ as an underlying layer with significantly reduced internal stresses and dislocation densities. As a result, the fabricated miniature LEDs obtain an external quantum efficiency of 9.1% and a peak wavelength of 672 nm at a current density of 0.4 A/cm2. Accordingly, this work confirms the potential for fabricating InGaN-based LEDs to achieve high-CRI mini/micro RGB displays. [ABSTRACT FROM AUTHOR]

One-dimensional van der Waals (1D vdW) materials, characterized by atomic chains bonded ionically or covalently in one direction and held together by van der Waals (vdW) interactions in the perpendicular directions, have recently gained intensive attention due to their exceptional functions. In this work, we report the discovery of one-dimensional (1D) ionic-bonded structures in NiSe nanowires. Utilizing aberration-corrected scanning transmission electron microscopy, we identified four distinct structural phases composed of two fundamental 1D building blocks: a triangle-shaped unit and a parallelogram-shaped unit. These phases can transform into one another through topotactic combinations of the structural units. Density functional theory calculations reveal that these structural units are bound by ionic bonds, unlike the van der Waals forces typically found in 1D vdW materials. The diverse arrangements of these building blocks may give rise to unique electronic structures and magnetic properties, paving the way for designing advanced materials with desired functionalities. [ABSTRACT FROM AUTHOR]

A normally-off field effect transistor with 15 nm LaB6 gate material directly deposited on hydrogen-terminated diamond surface has been fabricated and characterized. The reason for the normally-off operation could be attributed to the low work function of LaB6 layer, which can deplete holes in the channel. Due to the formation of C–B bond of interface and the thin thickness of LaB6, the subthreshold swing is as low as 70.6 mV/dec and interface state density is as low as 2 × 1011 cm−2eV−1. The maximum drain current density (IDSmax), extrinsic transconductance (Gm), threshold voltage (VTH), and on/off ratio for the device with 8-μm gate length are −60 mA/mm, 5 mS/mm, −1.1 V, and 109, respectively. The low-field mobility (μ0) without vertical-field degradation is 187 cm2/V s. The trapped charge density and fixed charge density are 8.75 × 1011 and 1.26 × 1012 cm−2, respectively. The LaB6/H-diamond logic inverters coupling with different load resistors show distinct inversion characteristics with a peak gain of 4.7 V/V. [ABSTRACT FROM AUTHOR]

The Stone–Wales (SW) defects have a critical impact on the physical properties of the carbon-based materials with pentagonal and hexagonal rings, which also emerge in other pentagon-based materials with the Cairo tessellation. However, scarce attention has been paid to SW defect engineering in two-dimensional (2D) pentagonal materials. In the present letter, we propose four unreported 2D PdSSe monolayers (designated as SW1–SW4) by introducing SW defects into the penta-PdSSe monolayer. The electronic structure, optical, electrical transport, and thermal transport properties of these SW defect structures have been systematically investigated based on first-principles calculations. SW1–SW4 retain the square-planar coordination as presented in the pristine penta-PdSSe, exhibiting excellent dynamical, thermal, and mechanical stability. Particularly, SW1 and SW2 exhibit direct bandgaps, which are more favorable for electronic transitions. The suitable band alignments meet the requirement of photocatalytic water splitting. Furthermore, the defect structures show high visible-light absorption coefficients (∼105 cm−1) and ultra-high carrier mobility (∼103 cm2V−1s−1). More excitingly, these defect structures display ultra-low anisotropic lattice thermal conductivities (lower than 2 Wm−1K−1 at room temperature). The suitable bandgap values, appropriate band edge positions, good optical absorption performances, and ultra-high carrier mobility concomitant with ultra-low lattice thermal conductivity render these PdSSe monolayers with SW defect structures as promising semiconductor materials for potential applications in nanoelectronics, optoelectronics, solar cell, photocatalyst, and thermoelectric energy conversions. [ABSTRACT FROM AUTHOR]

This study demonstrated InGaN-based flexible RGB micro-light-emitting diodes (μLEDs) with size ranging from 20 to 100 μm through laser liftoff and UV-tape-assisted transfer process. The fabrication process of flexible RGB μLEDs released the stress of GaN films, which reduced the bending of energy band and screened the quantum-confined Stark effect in InGaN quantum wells based on theoretical simulation. Thus, a clear blue shift of peak wavelength was observed especially for red μLEDs. The electrical and electroluminescent performance, such as forward voltage, peak wavelength, and full width half maximum of flexible RGB μLEDs, could remain approximately identical under different bending radii from 3 to 7 mm. We realized the monolithic integration of flexible RGB μLEDs and obtained a wide color gamut that covered around 78% of the Rec. 2020 at bending conditions. [ABSTRACT FROM AUTHOR]

In this study, we investigate in situ etching of β-Ga2O3 in a metalorganic chemical vapor deposition system using tert-butyl chloride (TBCl). We report etching of both heteroepitaxial 2 ¯ 01 -oriented and homoepitaxial (010)-oriented β-Ga2O3 films over a wide range of substrate temperatures, TBCl molar flows, and reactor pressures. We infer that the likely etchant is HCl (g), formed by the pyrolysis of TBCl in the hydrodynamic boundary layer above the substrate. The temperature dependence of the etch rate reveals two distinct regimes characterized by markedly different apparent activation energies. The extracted apparent activation energies suggest that at temperatures below ∼800 °C, the etch rate is likely limited by desorption of etch products. The relative etch rates of heteroepitaxial 2 ¯ 01 and homoepitaxial (010) β-Ga2O3 were observed to scale by the ratio of the surface energies, indicating an anisotropic etch. Relatively smooth post-etch surface morphology was achieved by tuning the etching parameters for (010) homoepitaxial films. [ABSTRACT FROM AUTHOR]

The trap and defect energy levels of ZnSnN2 and the current transport mechanism of its heterojunctions are studied. A shallow energy level at 105 meV below the conduction band minimum (Ec) of ZnSnN2 is detected and its possible origin is the intrinsic antisite defect of SnZn (Sn occupy the position of Zn in ZnSnN2), besides the traps located at 0.67, 1.03 and 1.06 to 1.21 eV below Ec. The interface states of ZnSnN2 heterojunctions form two discrete energy levels with one at Ec + 0.05 eV and another at Ec−0.03 eV. The current of ZnSnN2 heterojunctions is controlled by thermionic emission at relatively low bias voltage and limited by space charge at higher bias voltage. The barrier height of the heterojunctions is inhomogeneous, which obeys Gaussian distribution and possibly results from interface roughness. [ABSTRACT FROM AUTHOR]

Converting radiation into optical signals is a fundamental method for nuclear radiation detection. However, traditional scintillators encounter a trade-off between efficiency and response speed. This research proposes a radiation-photon converter constructed from multi-quantum-well (MQW) structures integrated into radiation-sensitive materials, providing a unique solution to this challenge. The prototype was fabricated using a homogeneous epitaxial layer of GaN on a semi-insulating substrate. The radiation-photon conversion process was facilitated by directing charge carriers generated from radiation energy deposited in the semi-insulating substrate to the MQW layer via an external electric field. The converter exhibited a sensitive and rapid response to x-ray irradiation, enabling modulation of the excited photon wavelength through the MQW layers. Luminescence spectrum tests demonstrated that the net luminescence intensity increased with rising device voltage. Imaging experiments revealed that the grayscale values of device photographs, under the combined influence of electric fields and x rays, correlated with the trend in net current variation. These findings confirmed the effective conversion of radiation into optical signals through the modulation mechanism of the electric field, highlighting significant implications for the development of advanced radiation detection methodologies. [ABSTRACT FROM AUTHOR]

We report the observation of two-dimensional hole gases (2DHGs) in N-polar AlGaN/GaN heterostructures grown on single-crystal GaN substrates by plasma-assisted molecular beam epitaxy. A systematic study varying AlGaN barrier thickness is performed. The presence of 2DHGs is confirmed by persistent p-type conductivity and high hole mobility observed in temperature-dependent Hall-effect measurements down to 10 K, and the dependence of 2DHG density on the AlGaN barrier thickness indicates its polarization induced origin. 2DHG with a sheet density of 7.5 × 10 12 cm−2 shows a relatively high hole mobility of 273 cm2 V−1 s−1 at 10 K. Mobility model fit suggests that acoustic phonon scattering is the dominant scattering mechanism in the sub-room temperature region. This work indicates that the quality of N-polar 2DHGs is comparable to that of state-of-the-art metal-polar 2DHGs, contributing to a building block for potential high-quality N-polar p-channel devices. [ABSTRACT FROM AUTHOR]

Metamaterial multipolar mode presents a compelling scheme for exploring fundamental properties and technological applications of light-matter interactions due to its strong near field and high quality factor. In this work, we demonstrate strong coupling and mode hybridization between metamaterial quadrupolar mode and molecular vibration in the mid-infrared. In our fabricated cross-shaped metasurfaces spin-coated with a polydimethylsiloxane (PDMS) film, a quadrupolar resonance with a quality factor of 33 is excited at oblique incidence, whose electric dipolar component efficiently couples to the Si-CH3 vibration with pronounced spectral splitting and anti-crossing behaviors. The coupling strength increases with the PDMS film thickness and reaches the strong coupling regime for thickness above 27 nm. A Rabi splitting of 0.79–1.13 THz is measured in the strong coupling regime. Our results indicate that the use of quadrupolar mode in plasmonic nanostructures provides an effective and convenient approach for the realization of vibrational polaritons, which hold promise for applications in ultrasensitive infrared sensing and photochemistry. [ABSTRACT FROM AUTHOR]

Traps filled in the off-state of high electron mobility transistors (HEMTs) are a primary factor contributing to the performance instability of power devices. These traps capture leakage electrons, causing instantaneous current fluctuations and drift of the threshold voltage. Realizing high spatial resolution measurements for off-state filled traps (OFTs) has become a prerequisite for optimizing device structure and exploring the device failure mechanism. However, the existing methods mainly detect the overall integral result of traps and are unable to indicate the in-plane distribution, which is unsatisfactory for studying the details of trap effects. In this paper, an approach for detecting the concentration and spatial distribution of OFT in GaN HEMTs has been proposed. The time constant and the energy level of OFT were first measured through the current transient analysis, and the local OFT intensity was then confirmed in off-state by measuring the change in electric field based on Raman spectroscopy. By adjusting the measurement position, the distribution of the OFT throughout the device is obtained. This method would contribute to the optimized design of wide-bandgap semiconductors. [ABSTRACT FROM AUTHOR]

The pursuit of high-efficiency and zero-emission refrigeration technologies has spurred interest in electrocaloric (EC) refrigeration utilizing ferroelectric (FE) materials, where accurate characterization of the EC effect is crucial for comprehending its underlying physical mechanisms and for developing high-performance EC materials. In this study, we investigate the influence of unsaturated vs saturated FE polarization characteristics on EC effects using Pb0.99Nb0.02[(Zr0.6Sn0.4)0.85Ti0.15]0.98O3 ceramics. Direct EC measurement reveals that unsaturated loops can introduce substantial errors and even fake negative EC effects when employing the Maxwell approach for indirect EC measurement. In contrast, relatively accurate indirect EC results can be obtained using saturated FE hysteresis loops. Furthermore, it also highlights the necessity for saturated polarization conditions to achieve optimal EC performance in FEs. This work not only emphasizes the importance of carefully selecting polarization data for indirect EC measurements, but also presents a universal strategy to enhance EC effects in various materials. [ABSTRACT FROM AUTHOR]

Identifying two-dimensional (2D) intrinsic magnetic materials is of great significance for revolutionized spintronic application and fundamental research. Through comprehensive first-principles calculations, we uncover a dynamical and thermally stable monolayer 2D transition metal dichalcogenide compound FeSe2 with an uncommon 1T′ structure and dimerized Fe–Fe bonds. More interestingly, the electronic structure of the 1T′-FeSe2 monolayer depends on the magnetic configurations. The ground state is a ferromagnetic (FM) metal with an obvious magnetocrystalline anisotropy and a high Curie temperature of nearly 400 K. In contrast, the nonmagnetic and antiferromagnetic (AFM) states are insulators, implying the FM to paramagnetic transition will be accompanied by a metal–insulator transition. Furthermore, the FM order transforms to AFM order under a 2.5% in-plane tension, accompanied by a metal–insulator transition. Intriguingly, the AFM trivial insulating state further evolves to AFM topological insulating state by further stretching the in-plane area with a tensile strain of ∼9.1%, which is attributed to the nonsymmorphic symmetry resulting from structural transition by breakdown of the dimerized Fe–Fe bonds. The present work not only is of great scientific interest in exploring unusual magnetic monolayer materials and fascinating phase transitions but also reveals the potential applications of 1T′-FeSe2 monolayers in nanoscale devices. [ABSTRACT FROM AUTHOR]

Polarization-induced two-dimensional electron gases (2DEGs) in AlN/GaN/AlN quantum well high-electron-mobility transistors on ultrawide bandgap AlN substrates offer a promising route to advance microwave and power electronics with nitride semiconductors. The electron mobility in thin GaN quantum wells embedded in AlN is limited by high internal electric field and the presence of undesired polarization-induced two-dimensional hole gases (2DHGs). To enhance the electron mobility in such heterostructures on AlN, previous efforts have resorted to thick, relaxed GaN channels with dislocations. In this work, we introduce n-type compensation δ -doping in a coherently strained single-crystal (Xtal) AlN/GaN/AlN heterostructure to counter the 2DHG formation at the GaN/AlN interface, and simultaneously lower the internal electric field in the well. This approach yields a δ -doped XHEMT structure with a high 2DEG density of ∼ 3.2 × 10 13 cm−2 and a room temperature (RT) mobility of ∼ 855 cm2/Vs, resulting in the lowest RT sheet resistance 226.7 Ω / □ reported to date in coherently strained AlN/GaN/AlN HEMT heterostructures on the AlN platform. [ABSTRACT FROM AUTHOR]

We investigate the resistive anisotropy in CsV3Sb5 thin films within the charge density wave phase. Using a device structure with twelve electrodes symmetrically distributed in a circular shape, we measure the resistivity anisotropy by varying the current direction. A twofold resistivity anisotropy modulated by temperature is found, which is fully consistent with the electronic nematicity in CsV3Sb5, that is, the spontaneous rotational symmetry breaking by electronic degree of freedom. Additionally, the resistivity anisotropy also shows modest changes by applying magnetic fields, implying the possible chiral charge orders with time-reversal symmetry breaking. These findings provide deep insights into the correlated electronic states in Kagome materials and highlight the unique properties of CsV3Sb5 in the two-dimensional regime. [ABSTRACT FROM AUTHOR]

Electrical manipulation of the antiferromagnetic states of Weyl semimetal Mn3Sn by current-induced spin–orbit torque (SOT) has attracted intensive attention recently, largely due to its potential advantage for high-density integration and ultrafast operation. In this study, the relation between the antiferromagnetic SOT switching ratio and the composition of Mn3+xSn1−x films was explored systematically. While SOT manipulation of ferromagnetic order has traditionally been confined to films just a few nanometers in thickness, our results indicate that current-induced SOT can effectively switch the antiferromagnetic order of sputtered Mn3+xSn1−x films with a thickness of up to 100 nm. Notably, a high electrical switching ratio of 83% was obtained in the optimized film with a composition of Mn3.1Sn0.9. The switching of the octupole polarization in thick Mn3Sn films may be accounted for by a seeded SOT mechanism. Joule heating of the Mn3Sn film close to the Néel temperature plays a key role in this switching process. Additionally, the factors influencing the switching ratio were further investigated. This work will deepen our understanding of the electrical switching mechanism of non-collinear antiferromagnetic order in Mn3Sn film and promote the development of antiferromagnetic spintronic devices. [ABSTRACT FROM AUTHOR]

Magnetic two-dimensional (2D) materials have garnered significant attention due to their unique electronic, magnetic, and optical properties and their potential applications in next-generation electronic and optoelectronic devices. However, the magneto-optical effects of oligolayer antiferromagnetic materials remain inadequately understood. Here, we investigate the magnetic properties of few-layer nickel phosphorus trisulfide (NiPS3) and its twisted heterostructures, emphasizing the observation of optical phenomena at low temperatures (1.65 K). By stacking few-layer NiPS3 to fabricate twisted homostructures, we probe their magnetic characteristics using photoluminescence (PL) spectroscopy. Our results reveal that sharp exciton peaks emerge at low temperatures and that the spin chain orientation in oligolayer NiPS3 can be discerned through the polarization dependence of exciton PL intensity. Notably, fewer-layered NiPS3 exhibits a significant magneto-optical effect under an applied magnetic field, allowing the modulation of the polarization angle of its exciton PL spectrum. Additionally, the polarization-dependent Raman spectrum of NiPS3 shows substantial changes under the influence of a magnetic field. These findings underscore the potential of few-layer NiPS3 for future magneto-optical device applications. [ABSTRACT FROM AUTHOR]

The macroscopic properties of piezoelectric materials can be profoundly influenced by stress. In this research, thermodynamic potential parameters of K0.4Na0.6NbO3 (KNN) single crystals have been experimentally quantified to assess the effects of stress. Leveraging the Landau thermodynamic potential theory, it has been identified that the application of biaxial tensile stress causes a significant elevation in both the piezoelectric property and phase transition temperature in KNN crystals. This transition remarkably extends their working range and improves the material's applicated potential. The coherence between these computational outcomes and experimental data—from the strategic growth of KNN single crystals with internal stress—underscores the reliability of our findings (dielectric constant from 213 to 1274, TO-T from 180 to 234 °C). Additionally, theoretical calculation predicts a potential enhancement in the piezoelectric capabilities of KNN single crystals. This study provides valuable insights for the growth of high-quality piezoelectric crystals and further promotes the application of lead-free piezoelectric materials. [ABSTRACT FROM AUTHOR]

Physical reservoir computing (PRC), a brain-inspired computing method known for its efficient information processing and low training requirements, has attracted significant attention. The key factor lies in the number of computational nodes within the reservoir for its computational capability. Here, we explore co-multiplexing reservoirs that leverage both temporal and spatial strategies. Temporal multiplexing virtually expands the node count through the use of masking techniques, while spatial multiplexing utilizes multiple physical locations (e.g., Hall bars) to achieve an increase in the number of real nodes. Our experiment employs a strain-mediated reservoir based on multiferroic heterostructures. By applying a single voltage across the PMN-PT substrate (acting as global input) and measuring the output Hall voltages from four Hall bars (real nodes), we achieve significant efficiency gains. This co-multiplexing approach results in a reduction in the normalized root mean square error from 0.5 to 0.23 for a 20-step prediction task of a Mackey–Glass chaotic time series. Furthermore, the single input and four independent outputs lead to a fourfold reduction in energy consumption compared to the strain-mediated PRC with temporal multiplexing solely. This research paves the way for future energy saving PRC implementations utilizing co-multiplexing, promoting a resource-efficient paradigm in reservoir computing. [ABSTRACT FROM AUTHOR]

Single-Event Burnout (SEB) can cause hard damage to devices, leading to permanent failure. However, previous studies have rarely explored the effects of high-energy proton irradiation-induced SEB in β-Ga2O3 Schottky Barrier Diode (SBD), and the underlying mechanisms remain largely unexplored. Experimental results indicate that the reverse bias voltage during irradiation is a critical factor influencing the failure of β-Ga2O3 SBD. Compared to 300 MeV proton irradiation without bias, the introduction of a 300 V reverse bias voltage results in a significant reduction in forward current density (JF). When the reverse bias voltage reaches 400 V or higher, the 300 MeV proton induces SEB in the device. The SEM image of the damaged region reveals that the irradiated device has "voids" formed due to the melting of the Ga2O3 material. Geant 4 and TCAD simulation results indicate that the burnout phenomenon is caused by the elevated lattice temperature inside the device, which results from the implantation of secondary particles under a high reverse bias voltage. As the reverse bias voltage increases, the maximum lattice temperature of β-Ga2O3 SBD also rises. When the reverse bias voltage is sufficiently high, the local lattice temperature inside the device reaches the melting point of Ga2O3 material, ultimately leading to SEB. [ABSTRACT FROM AUTHOR]

Due to their unique compositional, structural, and morphological characteristics, hydrogen bonded two-dimensional (2D) layered materials and their one-dimensional tubular derivatives are endowed with great importance in the fields of both fundamental sciences and potential applications. In this work, γ-AlOOH nanotubes have been synthesized via a template-free one-step solvothermal alcoholysis method. The pressure response of the samples under static compression is investigated by in situ high-pressure angle dispersive synchrotron x-ray diffraction techniques. The results indicate that the compression behavior of nanotubes is different from those of its counterparts in the bulk and the nanoflake form. At pressures below 9.4 GPa, the unit-cell parameters a, b, and c decrease monotonously with pressure. In the pressure range of 10.6–19.9 GPa, an unexpected negative linear compressibility along the c-axis is observed experimentally in the compression behavior. When the high pressure is gradually released, it is evidenced that the compression of the prepared γ-AlOOH nanotubes is irreversible. The observed abnormal compression behavior and the unexpected negative linear compressibility may be explained by inflation associated with incorporation of the pressure transmitting medium within the interior cavity of the tubular nanostructures. Such a counter-intuitive phenomenon may find potential applications under high pressures. [ABSTRACT FROM AUTHOR]

Nonlinear optics of structured light carrying orbital angular momentum (OAM) has recently led to intriguing fundamental physical effects in light–matter interactions and advanced applications from classical imaging to quantum informatics. However, the mutual interaction between spatial mode and frequency conversions in nonlinear processes is still elusive. In this work, we go beyond only considering OAM and frequency in nonlinear structured light conversion and investigate the complex mode evolution in cascaded nonlinear frequency conversion and spatial astigmatic mode conversion. In particular, we unveil a generalized law of nonlinear structured light from experiments and theories, that the converted modes are highly related to the sequence of frequency and spatial mode conversions, obeying an inherent (non)commutative rule in which. This effect not only creates extended structured laser modes but serves as regular rules in nonlinear optics. [ABSTRACT FROM AUTHOR]

We report the properties of molecular beam epitaxy deposited AlBN thin films on a recently developed epitaxial nitride metal electrode, Nb2N. While a control AlN thin film exhibits standard capacitive behavior, distinct ferroelectric switching is observed in the AlBN films with increasing Boron mole fraction. The measured remnant polarization P r ∼ 15 μC/cm2 and coercive field E c ∼ 1.45 MV/cm in these films are smaller than those recently reported on films deposited by sputtering, due to incomplete wake-up, limited by current leakage. Because AlBN preserves the ultrawide energy bandgap of AlN compared to other nitride hi-K dielectrics and ferroelectrics, and it can be epitaxially integrated with GaN and AlN semiconductors, its development will enable several opportunities for unique electronic, photonic, and memory devices. [ABSTRACT FROM AUTHOR]

The growth of VO2 epitaxial films has been researched extensively for obtaining excellent phase-transition performance. However, previous methods typically necessitate high temperatures or post-annealing processes, which elevate both experimental complexity and cost. In this work, we prepared high-quality VO2 epitaxial films by reactive magnetron sputtering directly under a low growth temperature. Benefiting from the determination of the oxygen pressure ratio from the theoretical analysis of the sputtering process model, single-stoichiometric VO2 epitaxial films could be prepared under 450 °C with a resistance change of 103, and above 500 °C with a resistance change exceeding 104. The mechanism of achieving low-temperature growth of VO2 epitaxial films was analyzed utilizing Thornton's zone model; finally, the epitaxial characteristics of VO2 on the sapphire substrate were confirmed from in-plane and out-of-plane directions. This work presents a guideline for the low-temperature growth of VO2 epitaxial films with enhanced phase-transition performance, thereby reducing both the cost and the requirements associated with the epitaxial growth of VO2 films. [ABSTRACT FROM AUTHOR]

This document is a collection of research papers on wide- and ultrawide-bandgap electronic semiconductor devices. It focuses on the progress and challenges in developing devices made from wide-bandgap materials like GaN, AlGaN, AlN, Ga2O3, BN, and diamond for power, rf, and photonic applications. The papers cover topics such as improving GaN power devices, exploring new wide bandgap materials, and investigating gate insulator properties. Additionally, there are papers on defect detection, new concepts for wide bandgap devices, and the growth and properties of different materials. The research provides valuable insights for researchers interested in using these materials in electronic devices. [Extracted from the article]

Inorganic CsPbI3 perovskite solar cells (PSCs) have garnered considerable attention due to their high thermal stability and promising application in tandem devices. However, further advancement of the performance of CsPbI3 PSCs is restricted by severe nonradiative recombination, which is related to substantial defects and mismatched energy levels. Herein, the versatile graphene quantum dots (GQDs) are introduced to modify the CsPbI3 surface to improve interface contact and mitigate energy loss. GQD modification can not only effectively passivate surface defects via coordinating with the undercoordinated Pb2+ but also improve energy level alignment, contributing to efficient charge extraction and suppression of nonradiative recombination. Consequently, GQDs-based inverted CsPbI3 devices deliver a champion power conversion efficiency (PCE) of 18.98% with a high open-circuit voltage (VOC) of 1.141 V and are greatly superior to the control device obtaining a poor PCE of 13.29% with a VOC of 0.986 V. Moreover, GQDs can form a protective layer at the perovskite interface to resist external invasion, significantly boosting the device stability. Our findings establish the promising application of GQD modification as a compelling strategy for achieving high performance inorganic photovoltaic devices. [ABSTRACT FROM AUTHOR]