High Breakdown Electric Field Research Articles

Development of \u03b2-Ga2O3 layers growth on sapphire substrates employing modeling of precursors ratio in halide vapor phase epitaxy reactor

Gallium oxide is a promising semiconductor with great potential for efficient power electronics due to its ultra-wide band gap and high breakdown electric field. Optimization of halide vapor phase epitaxy growth of heteroepitaxial upbeta-Ga2O3 layers is demonstrated using a simulation model to predict the distribution of the ratio of gallium to oxygen precursors inside the reactor chamber. The best structural quality is obtained for layers grown at 825–850 °C and with a III/VI precursor ratio of 0.2. Although the structural and optical properties are similar, the surface morphology is more deteriorated for the upbeta-Ga2O3 layers grown on 5 degree off-axis sapphire substrates compared to on-axis samples even for optimized process parameters. Cathodoluminescence with a peak at 3.3 eV is typical for unintentionally doped n-type upbeta-Ga2O3 and shows the appearance of additional emissions in blue and green region at ~ 3.0, ~ 2.8, ~ 2.6 and ~ 2.4 eV, especially when the growth temperatures is lowered to 800–825 °C. Estimation of the band gap energy to ~ 4.65 eV from absorption indicates a high density of vacancy defects.

Characteristics of silicon nitride deposited by very high frequency (162 MHz)-plasma enhanced atomic layer deposition using bis(diethylamino)silane

Silicon nitrides, deposited by capacitively coupled plasma (CCP)-type plasma enhanced atomic layer deposition (PEALD), are generally applied to today’s nanoscale semiconductor devices, and are currently being investigated in terms of their potential applications in the context of flexible displays, etc. During the PEALD process, 13.56 MHz rf power is generally employed for the generation of reactive gas plasma. In this study, the effects of a higher plasma generation frequency of 162 MHz on both plasma and silicon nitride film characteristics are investigated for the purpose of silicon nitride PEALD, using bis(diethylamino)silane (BDEAS) as the silicon precursor, and N2 plasma as the reactant gas. The PEALD silicon nitride film deposited using the 162 MHz CCP exhibited improved film characteristics, such as reduced surface roughness, a lower carbon percentage, a higher N/Si ratio, a lower wet etch rate in a diluted HF solution, lower leakage current, and higher electric breakdown field, and more uniform step coverage of the silicon nitride film deposited in a high aspect ratio trench, as compared to silicon nitride PEALD using 13.56 MHz CCP. These improved PEALD silicon nitride film characteristics are believed to be related to the higher ion density, higher reactive gas dissociation, and lower ion bombardment energy to the substrate observed in N2 plasma with a 162 MHz CCP.

(Invited) Photo-Electrochemical Etching and Porosification of III-Nitride Semiconductors

Gallium nitride (GaN), which is a III-nitride semiconductor, has wide direct bandgap (3.4 eV), high breakdown electric field (3.3x106 V/cm) and high saturation electron velocity (2.7 x107 cm/sec). On the basis of excellent optical and electrical properties, significant progress has been achieved in the GaN and III-nitride based devices, such as ultraviolet laser diodes, white light-emitting diodes, and high-frequency power transistors. In addition, GaN and its alloys are getting much attention as building block materials for electrochemical (EC) energy conversion systems such as chemical sensors, water splitting, and artificial photosynthesis due to their superior chemical stability, direct transition, and widely tunable bandgap by alloying. For the fabrication of nitride semiconductor devices, the plasma-assisted dry etching process has commonly been used. However, various types of damage and defects induced by the bombardment of reactive ions and radicals leads to severe operational stability problems in optical and electrical devices.Photo-electrochemical (PEC) etching probably solves these problems on nitride semiconductors. PEC etching possesses some big advantages such as low-damage process conducted at room temperature. In this presentation, we introduce our recent work on the PEC etching and porosification of III-nitride semiconductors. The etching features such as smooth and flat etching and porosification etching have been controlled by changing the PEC conditions [1,2]. The porous structure formed by the present method has attractive features such as a high-density array of pores exhibits high specific surface area, low reflectance, and high absorptance properties. In addition, this technique does not require any complicated process such as lithography, indicating higher productivity than other nanostructure fabrication techniques such as reactive ion etching and selective-area growth.One example is the formation of straight pores along with the electric field induced in the vertical to the GaN substrate. This kind of straight pores was formed in the dark condition under the high-electric filed applied. Here, we found that the pore diameter was enlarged by the irradiation of UV light to the GaN surface during the porosification. In the case of the irradiation of UV light with a photon energy (hv) above the bandgap energy (E g), the pore diameter was enlarged only in the top region with a depth less than 1µm, where the photo-absorption occurred only near the surface. On the other hand, under the illumination with hvbelow E g, the pore diameter was enlarged overall pore from the top to the bottom. This kind of photo-assisted etching can be explained by the sub-bandgap absorption during the porosification. Sub-bandgap light with a photon energy below the bandgap energy was transmitted through bulk GaN, but a certain type of photo-absorption additively occurred at the pore tip where high electric filed was concentrated. To confirm such specific absorption process, we systematically investigated the correlation between the photocurrents and photon energy by changing the light intensity. The photocurrents observed when the high-electric field was applied to n-GaN were well reproduced by calculation taking into account the Frantz-Keldysh effect [3]. The results suggest that the independent control of pore diameter and depth is possible by controlling the PEC conditions.Acknowledgement: This work was supported by JSPS KAKENHI-JP16H06421, 20H02175.[1] Y. Kumazaki et al., J. Appl. Phys., 121, 184501 (2017).[2] Y. Kumazaki et al., J. Electrochem. Soc., 164, H477 (2017).[3] M. Toguchi et al., J. Electrochem. Soc., 166, H510 (2019). Figure 1

A solution-processed La–Zr–O dielectric at a low temperature for high-performance In-Ga-O transistors: Engineering a precursor solution

For portable and low-power flexible devices, metal-oxide (M − O) materials offer high performance, superior stability, and a low-cost printing process that permits facile mass production. However, realization of printed flexible electronics using inorganic M − O materials has proven challenging because of obstacles associated with producing high-quality and dense dielectric films through a solution process at low temperatures. In this study, the effect of the solution stirring temperature and H2O2 loading on the structural and electrical properties of lanthanum zirconium oxide (LZO) dielectric films was investigated in detail. The surface roughness, mass density, and purity of H2O2–assisted LZO improved with increasing stirring temperature, resulting in a low leakage current of 4 × 10−8 A/cm2 at 2 MV/cm, a high-breakdown electric field of ~5.8 MV/cm, and relatively high permittivity (>12) at a low photochemical activation temperature of 180 °C for optimized LZO dielectric films. This can be attributed to the synergetic interaction of oxygen radicals introduced by H2O2 oxidants during deep ultraviolet photochemical annealing, causing hydrolysis of metal precursors, removal of organic residue, and formation of an M − O lattice. The fabricated indium gallium oxide thin-film transistor on a polyimide substrate at a maximum processing temperature of 180 °C exhibited a high mobility of 14.5 cm2/Vs, a high ION/OFF ratio of 107, negligible hysteresis, and a small driving voltage range (−2 to 2 V).

Solar-blind imaging based on 2-inch polycrystalline diamond photodetector linear array

Diamond is a promising ultrawide-bandgap semiconductor, which has drawn much attention in deep-ultraviolet optoelectronics and high-power electronics, due to its unique properties, including the highest thermal conductivity, strong radiation resistance, high breakdown electric field, chemical and thermal stability, and high carrier mobility. However, the optoelectronics applications have been restricted greatly by the small growth size of the single-crystal diamond. In this work, we demonstrate a solar-blind photodetector linear array based on high-quality 2-inch polycrystalline diamond, which has the advantage of large-area growth. The photodetector cells exhibit good uniformity, a responsivity of 45 mA/W at 228 nm with a cut-off wavelength of 240 nm, and a short response time of <20 μs. Clear solar-blind images are obtained by using the photodetector linear array as sensing units. The results reported in this work promise the potential applications of polycrystalline diamond in deep-ultraviolet photodetectors.

Design of Lead-Free Films with High Energy Storage Performance via Inserting a Single Perovskite into Bi4Ti3O12 * *Supported by the National Natural Science Foundation of China (Grant Nos. 11864028 and 12074204).

We report a distinctive way for designing lead-free films with high energy storage performance. By inserting different single perovskite cells into Bi4Ti3O12, P–E hysteresis loops present larger maximum polarization, higher breakdown strength and smaller slim-shaped area. We prepared 0.15Bi7Fe3Ti3O21-0.5Bi4Sr3Ti6O21-0.35Bi4Ba3Ti6O21 solid solution ferroelectric films employing the sol-gel method, and obtained high energy storage density of 132.5 J/cm3 and efficiency of 78.6% while maintaining large maximum polarization of 112.3 μC/cm2 and a high breakdown electric field of 3700 kV/cm. Moreover, the energy storage density and efficiency exhibit stability over the temperature range from 20 °C to 125 °C, and anti-fatigue stability maintains up to 108 cycles. The films with a simple preparation method and high energy storage performance are likely to become candidates for high-performance energy storage materials.

Characterization of β-Ga2O3 homoepitaxial films and MOSFETs grown by MOCVD at high growth rates

The ultra-wide bandgap semiconductor gallium oxide (Ga2O3) offers substantial promise to significantly advance power electronic devices as a result of its high breakdown electric field and maturing substrate technology. A key remaining challenge is the ability to grow electronic-grade epitaxial layers at rates consistent with 20–40 μm thick drift regions needed for 20 kV and above technologies. This work reports on extensive characterization of epitaxial layers grown in a novel metalorganic chemical vapor deposition tool that permits growth rates of 1.0–4.0 μm h−1. Specifically, optical, structural and electrical properties of epilayers grown at ∼1 μm h−1 are reported, including employment in an operating MOSFET. The films demonstrate relatively smooth surfaces with a high degree of structural order, limited point defectivity (Nd − Na ≈ 5 × 1015 cm−3) and an optical bandgap of 4.50 eV. Further, when employed in a MOSFET test structure with an n+ doped channel, a record high mobility for a transistor structure with a doped channel of 170 cm2 V−1 s−1 was measured via the Hall technique at room temperature. This work reports for the first time a β-Ga2O3 MOSFET grown using Agnitron Technology’s high growth rate MOCVD homoepitaxial process. These results clearly establish a significant improvement in epilayer quality at growth rates that can support future high voltage power device technologies.

Excellent Capacitor-Varistor Properties in Lead-Free CaCu3Ti4O12-SrTiO3 System with a Wrinkle Structure via Interface Engineering.

Lead-free perovskite CaCu3Ti4O12 (CCTO) dielectrics are extremely important candidates for capacitor-varistor dual-function materials. However, their overall success in applications is somewhat controlled by the longstanding issues such as relatively large dielectric loss and insufficiently high electric breakdown field. Herein, we report the success in the preparation of an optimized lead-free (1-x)CaCu3Ti4O12-xSrTiO3 (CCTO-STO) composite system with improved dielectric and nonlinear properties via interface engineering. Interestingly, looking closer at the grain boundaries using transmission electron microscopy, it is found that an obvious interface region with a transition layer of a wrinkled structure is formed between the CCTO matrix phase and STO dopant phase. Significantly, all the composite ceramic samples present high permittivity in the order of about 103 to 104, and the 0.9CCTO-0.1STO composite ceramic sample exhibits a lower dielectric loss of about 0.068 at room temperature and at 1 kHz. Excitingly, the optimized 0.9CCTO-0.1STO composite ceramic sample also exhibits a remarkably elevated breakdown field strength of about 14.03 kV/cm and a large nonlinear coefficient of about 16.11. The improvement in nonlinear properties with a high breakdown field strength and large nonlinear coefficient could be attributed to the interfacial effect in the composite structure, originating from the formation of the transition layer with a wrinkle structure at the interface between CCTO and STO phases. Such effects can result in great electrical heterogeneity caused by the higher resistance of the grain boundary and the enhanced potential barrier at the interface region. The new insights on the formation of the interfacial wrinkle structure near the phase boundaries of the CCTO-STO composite system and their effects on improvement of electrical properties can stimulate future research on lead-free CCTO-STO-based systems toward capacitor-varistor dual-function applications and may offer an effective way to design other lead-free dielectric materials as well.

Development of graphene oxide – PDMS composite dielectric for rapid droplet movement in digital microfluidic applications

Dielectric breakdown puts an operating limit to the applied electric field in electrowetting-based applications. Herein, we report that the electrical properties relevant to electrowetting for a widely used dielectric, PDMS, can be substantially enhanced upon the incorporation of graphene oxide (GO) fillers into the PDMS polymer matrix. The GO-PDMS composite is characterized by higher values of the dielectric constant, higher breakdown electric field, and lower actuation voltages due to enhanced interfacial polarization. The improvement of these properties with the increase in concentration of GO, is explored till the ‘percolation threshold’. This newly developed composite as the dielectric, droplet actuation and electric field-induced droplet transportation over a fabricated triangular electrode system are performed. The results are compared with the literature data on PDMS and other dielectrics to establish the superior qualities of the dielectric for rapid transportation of droplets at significantly lower voltages with potential for new applications.

Analysis of Dislocations in PVT-Grown 6H-SiC through Grazing-Incidence X-Ray Topographic Images and Ray-Tracing Simulation

The superior electronic and physical properties of silicon carbide (SiC), such as wide band-gap, high saturated electron velocity, high breakdown electric field strength, and high thermal conductivity, enable successful applications in modern power electronic devices with high power, high frequency, and high temperature operation requirements. [1,2] Therefore, understanding the nature and behavior of different dislocations is of great significance towards crystal quality enhancement. Synchrotron X-ray has been widely adopted for generating topographic images of threading screw dislocations (TSDs) as well as threading edge dislocations (TEDs) and basal plane dislocations (BPDs). Besides, recent study in 4H-SiC revealed the presence of threading mixed dislocations (TMDs) with Burgers vectors nc+ma (where m and n are integers). [3] Since direct TMDs observation methods such as transmission electron microscopy (TEM) and synchrotron white-beam X-ray topography (SWBXT) are not suitable for commercially preferred c-plane-oriented wafers, ray-tracing simulated images of possible dislocation types are compared with X-ray topographs in order to identify the TMDs non-destructively. Except 4H-SiC, ray-tracing simulation has also been proved as an effective approach for dislocation characterization in various materials such as GaN [4], ZnO [5], and AlN [6]. The same principle is implemented in this study for the investigation of dislocations in 6H-SiC wafer.Synchrotron monochromatic beam X-ray topography (SMBXT) analysis was carried out on a PVT grown 6H-SiC wafer for recording its grazing-incidence images of all six different 11-212 reflections (Fig. 1). The distribution of TSDs, TEDs, TMDs, and BPDs are characterized, and the determination of their Burgers vectors is achieved by correlating the simulated results obtained through ray-tracing simulation with real X-ray topographic observations (Fig. 2). This study provides a clear understanding of dislocations in 6H-SiC, which is crucial for quality improvement of the crystal.Reference:[1]: C. Codreanu, et al, Comparison of 3C-SiC, 6H-SiC and 4H-SiC MESFETs Performances, Materials Science in Semiconductor Processing 3 137 (2000).[2]: J. W. Sun, et al, Shockley-Frank Stacking Faults in 6H-SiC, Journal of Applied Physics 111, 113527 (2012).[3]: J. Q. Guo, et al, Direct Determination of Burgers Vectors of Threading MixedDislocations in 4H-SiC Grown by PVT Method, Journal of Electronic Materials 45, 4 (2016).[4]: B. Raghothamachar, et al, X-ray Topography Characterization of Gallium Nitride Substrates for Power Device Applications, submitted for publication.[5]: T. Y. Zhou, “Threading Dislocation Characterization and Stress Mapping Depth Profiling via Ray Tracing Technique,” Ph.D. Thesis, SUNY Stony Brook, Advisor: Michael Dudley (2015).[6]: T. Y. Zhou, et, al, Characterization of Threading Dislocations in PVT-Grown AlN Substrates via x-Ray Topography and Ray Tracing Simulation, Journal of Electronic Materials volume 43, 838 (2014). Figure 1

Enhanced energy storage performances of CaTiO3-based ceramic through A-site Sm3+ doping and A-site vacancy

Ceramic-based capacitors for energy storage devices require simultaneously high energy density and efficiency. Achieving high electric breakdown field based on linear dielectrics is crucial. Here, A-site Sm3+ doped perovskite Ca1-1.5xSmx□0.5xTiO3 ceramics with introduced A-site vacancies (VA) were prepared. All Ca1-1.5xSmx□0.5xTiO3 ceramics crystallize in an orthorhombic structure, with lattice constants a, b, and c linearly decreased. As a result of Sm3+ dopants and VA, the grain size decreased while the ceramics’ density was improved. The permittivity decreases from 176 (x = 0) to 135 (x = 0.1), but tanδ is effectively constrained (∼10−4). What’s more, the dielectric breakdown strength is significantly improved from 429 kV/cm (x = 0) to 547 kV/cm (x = 0.1) with dielectric linearity is maintained. The optimum energy storage density of 2 J/cm3 (x = 0.02) with ultrahigh energy efficiency of over 93.7 % is achieved, which are superior to many existing linear dielectrics and relaxor ferroelectrics. This work confirms the energy-storage enhancement through chemical modifications and microstructural engineering.

Thermal Transport across Ion-Cut Monocrystalline β-Ga2O3 Thin Films and Bonded β-Ga2O3-SiC Interfaces.

The ultrawide band gap, high breakdown electric field, and large-area affordable substrates make β-Ga2O3 promising for applications of next-generation power electronics, while its thermal conductivity is at least 1 order of magnitude lower than other wide/ultrawide band gap semiconductors. To avoid the degradation of device performance and reliability induced by the localized Joule-heating, proper thermal management strategies are essential, especially for high-power high-frequency applications. This work reports a scalable thermal management strategy to heterogeneously integrate wafer-scale monocrystalline β-Ga2O3 thin films on high thermal conductivity SiC substrates by the ion-cutting technique and room-temperature surface-activated bonding technique. The thermal boundary conductance (TBC) of the β-Ga2O3-SiC interfaces and thermal conductivity of the β-Ga2O3 thin films were measured by time-domain thermoreflectance to evaluate the effects of interlayer thickness and thermal annealing. Materials characterizations were performed to understand the mechanisms of thermal transport in these structures. The results show that the β-Ga2O3-SiC TBC values are reasonably high and increase with decreasing interlayer thickness. The β-Ga2O3 thermal conductivity increases more than twice after annealing at 800 °C because of the removal of implantation-induced strain in the films. A Callaway model is built to understand the measured thermal conductivity. Small spot-to-spot variations of both TBC and Ga2O3 thermal conductivity confirm the uniformity and high quality of the bonding and exfoliation. Our work paves the way for thermal management of power electronics and provides a platform for β-Ga2O3-related semiconductor devices with excellent thermal dissipation.

Ga2O3 solar-blind position-sensitive detectors

Monoclinic Ga2O3 (β-Ga2O3) is a promising material for achieving solar-blind photodetection because of its unique characteristics, including its high breakdown electric field, radiation hardness, thermal and chemical stabilities, and intrinsic visible/solar-blind properties. Until now, several studies have investigated the development of high-performance β-Ga2O3 solar-blind photodetectors. However, these photodetectors can only detect the light intensity but not the light position. In this work, four-quadrant position-sensitive detectors (4Q-PSDs) were developed and demonstrated based on β-Ga2O3. 4Q-PSDs, comprising four identical metal-semiconductor-metal-structured photodetector components, demonstrate high uniformity, large signal-to-noise ratio, good ultraviolet/visible rejection ratio, and fast response/recovery time. Subsequently, the position of the illumination beam can be determined by analyzing the output signals of the four photodetector components. This work may indicate the promising application potential of the Ga2O3-based photodetectors in the fields of positioning, aligning, and monitoring the solar-blind beams.

Growth of High-Quality Hexagonal Boron Nitride Single-Layer Films on Carburized Ni Substrates for Metal-Insulator-Metal Tunneling Devices.

Two-dimensional (2D) hexagonal boron nitride (h-BN) plays a significant role in nanoscale electrical and optical devices because of its superior properties. However, the difficulties in the controllable growth of high-quality films hinder its applications. One of the crucial factors that influence the quality of the films obtained via epitaxy is the substrate property. Here, we report a study of 2D h-BN growth on carburized Ni substrates using molecular beam epitaxy. It was found that the carburization of Ni substrates with different surface orientations leads to different kinetics of h-BN growth. While the carburization of Ni(100) enhances the h-BN growth, the speed of the h-BN growth on carburized Ni(111) reduces. As-grown continuous single-layer h-BN films are used to fabricate Ni/h-BN/Ni metal-insulator-metal (MIM) devices, which demonstrate a high breakdown electric field of 12.9 MV/cm.

Thickness-dependent thermal conductivity of mechanically exfoliated β -Ga2O3 thin films

Beta-phase gallium oxide (β-Ga2O3), the most thermally stable phase of Ga2O3, has stimulated great interest in power electronics due to its ultra-wide bandgap (∼4.9 eV) and high breakdown electric field. The relatively low thermal conductivity of β-Ga2O3, however, limits the device performance due to excessive temperature driven by self-heating. Recently, integrating β-Ga2O3 thin films on substrates with high thermal conductivities has been proposed to improve heat rejection and device reliability. In this work, we prepare high-quality single-crystal β-Ga2O3 thin films by mechanical exfoliation of bulk crystals and study their thermal transport properties. Both the anisotropic thermal conductivity of β-Ga2O3 bulk crystals and the thickness-dependent thermal conductivity of β-Ga2O3 thin films are measured using the time-domain thermoreflectance technique. The reduction in the thin-film thermal conductivity, compared to the bulk value, can be well explained by the size effect resulting from the enhanced phonon-boundary scattering when the film thickness decreases. This work not only provides fundamental insight into the thermal transport mechanisms for high-quality β-Ga2O3 thin films but also facilitates the design and optimization of β-Ga2O3-based electronic devices.

Spark plasma sintering of SnO2 based varistors

In this research, for the first time, SnO2-based varistors were fabricated via spark plasma sintering technique (SPS) and the microstructure and electrical properties of these varistors were investigated. Furthermore, the effect of post-annealing temperature in oxygen atmosphere on electrical properties of the SPSed samples was studied. The SPS process was performed at the sintering temperatures of 600, 650, and 700 ᵒC for 15 min with a maximum pressure of 90 MPa under vacuum condition. The SPSed sample which was sintered at 650 ᵒC possessed maximum density of 98% and the ultra-fine-grained microstructure with the mean grain size of 380 nm. Surprisingly, all SPSed samples exhibited Ohmic behavior with very low electric resistances. After post-annealing in oxygen atmosphere, Ohmic to non-Ohmic transition was observed in SPSed samples. The oxygen deficiency during the SPS process was responsible for the Ohmic characteristic of SPSed samples. Post-annealing of SPSed samples in the oxygen atmosphere resulted in Schottky barriers formation through oxygen adsorption at grain boundaries. The sample post-annealed at 1050 ᵒC presented the best non-Ohmic parameters including high breakdown electric field of 4500 V/cm and the nonlinear coefficient of 13. These electrical parameters are comparable with the conventional-sintered samples which was sintered at 1300 ᵒC and its breakdown electric field and nonlinear coefficient were equal to 900 V/cm and 8, respectfully.

Discovery of New Polymorphs of Gallium Oxides with Particle Swarm Optimization‐Based Structure Searches

AbstractGallium oxide (Ga2O3) has attracted significant research interest for next‐generation high‐efficiency power devices because of its unique electronic properties such as ultra‐wide band gap, high breakdown electric field, and large Baliga’s figure of merit. Ga2O3 crystallizes in a series of reported polymorphs including β‐, α‐, ε‐, κ‐, γ‐, and δ‐Ga2O3, the structures of some of which are still in serious controversy. A polymorph structure search study of Ga2O3 is herein performed by combining particle swarm optimization with first‐principles energetic calculations. In addition to producing the predominant experimental known phases of β‐, α‐, and κ‐Ga2O3, two new polymorphs are found with space group P and Pmc21 consisting of four‐ and five‐fold coordinated Ga. They show comparable energy with β‐ and α‐Ga2O3 with the energy difference of several meV per atom, and exhibit robust phonon stability. Similarly, the new phases show quite wide band gaps and small electron effective masses by comparing it with other known phases. The Pmc21 phase shows a calculated spontaneous polarization of 0.277 C m−2, close to that of ε/κ‐Ga2O3. The systemic structure searches also establish a structural relationship between ε‐Ga2O3 and κ‐Ga2O3 and how the electronic properties vary with polymorphic phase change.

Low‐Voltage Heterojunction Metal Oxide Transistors via Rapid Photonic Processing

AbstractSolution‐processed metal oxide thin‐film transistors (TFTs) represent a promising technology for applications in existing but also emerging large‐area electronics. However, high process temperatures and lengthy annealing times represent two remaining technical challenges. Different approaches aiming to address these challenges have been proposed but progress remains modest. Here, the development of high electron mobility metal oxide TFTs based on photonically converted Al2O3/ZrO2 and In2O3/ZnO bilayers acting as the high‐k dielectric and electron‐transporting channel, respectively is described. Sequential solution‐phase deposition and photonic processing lead to low substrate temperature (&lt;200 °C) while minimizing the overall process time to less than 60 s without compromising the quality of the formed layers. The bilayer Al2O3/ZrO2 dielectric exhibits low leakage current density (10−6 A cm−2 at 1 MV cm−1), high geometric capacitance (≈120 nF cm−2) and breakdown electric field of ≈1 MV cm−1. Combining Al2O3/ZrO2 with a photonically converted In2O3/ZnO heterojunction channels, results in TFTs with high electron mobility (19 cm2 V−1 s−1), low operation voltage (≤2 V), high current on/off ratio (&gt;106), and low subthreshold swing (108 mV dec−1), that can be manufactured even onto thermally sensitive polymer substrates. The work is a significant step toward all‐photonic processed metal oxide electronics.

Fabrication of silicon on insulator wafer with silicon carbide insulator layer by surface-activated bonding at room temperature

We propose a process for the fabrication of a silicon-on-insulator (SOI) wafer with a silicon carbide (SiC) insulator layer by combining plasma-enhanced chemical vapor deposition and surface-activated bonding without thermal stress to obtain sufficient thermal conductivity for self-heating power and high-frequency device applications. The thermal conductivity of the deposited SiC layer is twice that of a silicon dioxide (SiO2) layer, and the breakdown electric field of this layer is 10–11 MV cm−1, the same as that of a SiO2 layer. In addition, the bonding interface between the silicon layer and the deposited SiC insulator layer has no voids or punch-out dislocations. Therefore, the SOI wafer with a SiC layer has high thermal conductivity and breakdown electric field; this SOI wafer and its fabrication process will be important for the realization of next-generation self-heating devices such as power and high-frequency devices.

Energy storage performance in polymer dielectrics by introducing 2D SrBi4Ti4O15 nanosheets

Polymer-based dielectric energy storage materials have been playing critical roles in high-performance energy storage capacitors due to their high breakdown electric fields and facile processability. However, the low energy density and efficiency of polymer-based film capacitors limit their widespread application in various electronics products. In this contribution, we synthesized the SrBi4Ti4O15 (SBT) nanosheets with large aspect ratio by using the molten salt method and introduced them into the PVDF matrix to prepare a multilayer nanocomposite film, of which the discharge energy density and discharge efficiency were much improved. Finite element simulation results show that the addition of 2D SBT nanosheets can significantly improve the local electric field distribution of nanocomposite films. Finally, a high discharge energy density of 11.69 J cm−3 and an excellent discharge efficiency of 78.95% were simultaneously achieved in the 0/5/0 sample. This work provides a reference for polymer-based dielectrics with excellent comprehensive energy storage performance.