Showing papers by "Jiandong Ye published in 2022"
TL;DR: In this paper, the authors implemented beveled-mesa NiO/Ga2O3 p-n heterojunction diodes (HJDs) into a 500-W power factor correction (PFC) system circuit, achieving high conversion efficiency of 98.5% with 100-min stable operating capability.
Abstract: The technical progress of Ga2O3 power diodes is now stuck at a critical point where a lack of performance evaluation and reliability validation at the system-level applications seriously limits their further development and even future commercialization. In this letter, by implementing beveled-mesa NiO/Ga2O3 p–n heterojunction diodes (HJDs) into a 500-W power factor correction (PFC) system circuit, high conversion efficiency of 98.5% with 100-min stable operating capability has been demonstrated. In particular, rugged reliability is validated after over 1 million times dynamic breakdown with a 1.2-kV peak overvoltage. Meanwhile, superior device performance is achieved, including a static breakdown voltage (BV) of 1.95 kV, a dynamic BV of 2.23 kV, a forward current of 20 A (2 kA/cm2 current density), and a differential specific on -resistance of 1.9 mΩ·cm2. These results indicate that Ga2O3 power HJDs are developing rapidly with their own advantages, presenting the enormous potential in high-efficiency, high-power, and high-reliability applications.
49 citations
TL;DR: In this paper , a vertical β-Ga2O3 Schottky barrier diode (SBD) with the advanced termination structure of p-type NiOx and n-type β-GAspO3 heterojunctions and coupled field plate structures to alleviate the crowding electric field was acquired, yielding a state-of-the-art direct current Baliga's power figure of merit of 1.11
Abstract: This work acquires a vertical β-Ga2O3 Schottky barrier diode (SBD) with the advanced termination structure of p-type NiOx and n-type β-Ga2O3 heterojunctions and coupled field plate structures to alleviate the crowding electric field. A Ga2O3 SBD delivers an average breakdown voltage of 1860 V and a specific on-resistance of 3.12 mΩ cm2, yielding a state-of-the-art direct-current Baliga's power figure of merit of 1.11 GW/cm2 at an anode area of 2.83 × 10−5 cm2. In addition, the Ga2O3 SBD with the same fabrication process at a large area of 1.21 × 10−2 cm2 also presents a high forward current of 7.13 A, a breakdown voltage of 1260 V, and a power figure-of-merit of 235 MW/cm2. According to dynamic pulse switching and capacitance-frequency characteristics, an optimized p-NiOx/Ga2O3 interface with a maximum trap density of 4.13 × 1010 eV−1 cm−2 is delivered. Moreover, based on the forward current-voltage measurement at various temperatures, the physics behind a forward conduction mechanism is illustrated. Ga2O3 SBDs with p-NiOx/n-Ga2O3 heterojunction termination, field plate, high power figure of merit, and high quality interface as well as suppressed resistance increase after dynamic pulse switching, verifying their great promise for future high power applications.
23 citations
TL;DR: Investigation of majority and minority carrier traps in beta-gallium oxide by means of deep level transient spectroscopy (DLTS) in Ni and both diodes determined to be bipolar HJD.
Abstract: Identifying defects/traps is of vital importance for the implementation of high-performance Ga2O3 power devices. In this work, majority and minority carrier traps in beta-gallium oxide ( $\beta $ -Ga2O3) have been investigated and identified by means of deep level transient spectroscopy (DLTS) in Ni/ $\beta $ -Ga2O3 Schottky barrier diode (SBD) and NiO/ $\beta $ -Ga2O3 p+-n heterojunction diode (HJD). For both diodes, a dominant energy level of majority carrier (electron) trap states is determined to be ${E}_{C}-$ (0.75–0.79) eV with a concentration of (2.4–4.1) $\times 10^{{13}}$ cm $^{-{3}}$ . Meanwhile, an additional trapping level at ${E}_{V} +0.14$ eV with a concentration of 1.2 $\times 10^{{14}}$ cm $^{-{3}}$ yield is present in NiO/ $\beta $ -Ga2O3 bipolar HJD but absent in the Ni/ $\beta $ -Ga2O3 SBD unipolar counterpart. The detection of such minority carrier traps originates from the hole injection through trap-assisted tunneling (TAT) from $\text{p}^{+}$ -NiO to $\beta $ -Ga2O3. The bias- and frequency-dependent DLTS characteristics identify that such shallow-level minority carrier traps are located in the $\beta $ -Ga2O3 bulk region rather not interfacial states at the NiO/ $\beta $ -Ga2O3 heterointerface. The identification of both majority and minority carrier traps in this work may shed light on the in-depth understanding of carrier transport mechanisms in Ga2O3-based unipolar and bipolar power devices.
16 citations
TL;DR: A compact label-free nanosensor based on a fiber taper and zinc oxide nanogratings is designed and applied for the early monitoring of apoptosis in individual living cells and provides a new platform for nonfluorescent fiber devices for investigation of cellular events and understanding fundamental cell biochemical engineering.
Abstract: Abstract. The achievement of functional nanomodules for subcellular label-free measurement has long been pursued in order to fully understand cellular functions. Here, a compact label-free nanosensor based on a fiber taper and zinc oxide nanogratings is designed and applied for the early monitoring of apoptosis in individual living cells. Because of its nanoscale dimensions, mechanical flexibility, and minimal cytotoxicity to cells, the sensing module can be loaded in cells for long term in situ tracking with high sensitivity. A gradual increase in the nuclear refractive index during the apoptosis process is observed, revealing the increase in molecular density and the decrease in cell volume. The strategy used in our study not only contributes to the understanding of internal environmental variations during cellular apoptosis but also provides a new platform for nonfluorescent fiber devices for investigation of cellular events and understanding fundamental cell biochemical engineering.
11 citations
TL;DR: In this article , a paper-based thermal radiation-enabled evaporation system (TREES) is demonstrated to achieve sustainable and highly efficient salt-collecting desalination, featuring a dynamic evapse front based on the accumulated salt layer where water serves as its own absorber via energy down-conversion.
Abstract: Solar desalination is expected to solve the problem of global water shortage. Yet its stability is plagued by salt accumulation. Here, a paper-based thermal radiation-enabled evaporation system (TREES) is demonstrated to achieve sustainable and highly efficient salt-collecting desalination, featuring a dynamic evaporation front based on the accumulated salt layer where water serves as its own absorber via energy down-conversion. When processing 7 wt % brine, it continuously evaporates water at a high rate─2.25 L m-2 h-1 under 1 sun illumination─which is well beyond the input solar energy limit for over 366 h. It is revealed that such enhanced evaporation arises from the unique vertical evaporation wall of the paper-TREES, which captures the thermal energy from the heated bottom efficiently and gains extra energy from the warmer environment. These findings provide novel insights into the design of next-generation salt-harvesting solar evaporators and take a step further to advance their applications in green desalination.
10 citations
TL;DR: In this paper , the most effective addition content of calcium silicate (CaSiO3, CS) in promoting the in vitro osteogenesis was first sorted out, and then the effective zinc doping content in CS for improving osteogenic differentiation of CPC-based composites was screened out.
Abstract: Calcium phosphate cement (CPC), a popular injectable bone defect repairing material, has deficiencies in stimulating osteogenesis and angiogenesis. To overcome the weaknesses of CPC, zinc-doped calcium silicate (Zn-CS) which can release bioactive silicon (Si) and zinc (Zn) ions was introduced to CPC. The physicochemical and biological properties of CPC and its composites were evaluated. Firstly, the most effective addition content of calcium silicate (CaSiO3, CS) in promoting the in vitro osteogenesis was first sorted out. On this basis, the most effective Zn doping content in CS for improving osteogenic differentiation of CPC-based composites was screened out. Finally, the immunoregulation of CS/CPC and Zn-CS/CPC in promoting angiogenesis and osteogenesis was studied. The results showed that the most effective incorporation content of CS was 10 wt%. Zn at a doping content of 30 mol% in CS (30Zn-CS) further enhanced the osteogenic capacity of CS/CPC and simultaneously maintained excellent proangiogenic activity. CS/CPC and 30Zn-CS/CPC promoted the recruitment of macrophages and enhanced M2 polarization while inhibiting M1 polarization, which was beneficial to the early vascularization as well as subsequent new bone formation. When implanted into the femoral condylar defects of rabbits, 30Zn-CS/CPC showed high in vivo materials degradation rate, angiogenesis and osteogenesis, due to the synergistic effects of Si and Zn on bio-stimulation and immunoregulation. This study shed light on the synergistic effects of Si and Zn on regulating the angiogenic, osteogenic, and immunoregulatory activity, and 30Zn-CS/CPC is expected to repair the lacunar bone defects effectively.
10 citations
TL;DR: In this paper , a high performance and cost-effective NO2 gas sensor operating at room temperature was realized from synthesized SnO2 nanospheres functionalized with Pd nanoparticles and rGO nanosheets (Pd-SnO2/rGO) by a facile one-step hydrothermal route.
9 citations
TL;DR: In this paper, a high performance and cost-effective NO2 gas sensor operating at room temperature was realized from synthesized SnO2 nanospheres functionalized with Pd nanoparticles and rGO nanosheets (Pd-SnO2/rGO) by a facile one-step hydrothermal route.
9 citations
TL;DR: In this article , the authors demonstrate the performance of a lateral superjunction (SJ)-equivalent MOSFET with a selective epitaxial filling of p-NiO pillars into the trenched drift region.
Abstract: In this work, we, for the first time, demonstrate $\beta $ -Ga2O3 lateral superjunction (SJ) -equivalent metal–oxide–semiconductor field-effect transistors (MOSFETs). The electric field engineering is implemented by the alternatively arranged p-NiO/n-Ga2O3 lateral hetero-SJ, which is constructed through the selective epitaxial filling of p-NiO pillars into the trenched drift region of $\beta $ -Ga2O3. The static electrical characteristics indicate that $\beta $ -Ga2O3 SJ-equivalent MOSFETs outperform the control transistor without the SJ structure. In particular, the Ga2O3SJ-equivalent MOSFET with a p-NiO pillar width of 2 $\mu \text{m}$ demonstrates a breakdown voltage ( ${V}_{\text {br}}$ ) of 1362 V and a power figure-of-merit (PFOM) of 39 MW/cm2, which are 2.42 and 4.86 times higher, respectively, than those of the control device. The large divergence of the experimental performance from the theoretical predictions is attributed to the charge imbalance caused by the substrate-assisted depletion effect and superimposed interfacial charges. With the proper interface engineering and controlled doping, it is expected that utilizing p-NiO/n-Ga2O3 hetero-SJ is a promising technological strategy to allow a favorable trade-off between ${V}_{\text {br}}$ and ON-state loss of Ga2O3 transistors for the high-efficiency power conversion.
8 citations
TL;DR: In this article , the authors systematically study the performance limits of sub-10 nm (6.4-9.6 nm) monolayer (ML) AsP TFETs by means of ab initio quantum transport calculation.
8 citations
TL;DR: In this article , high performance solar-blind photodetectors fabricated on the m-plane using the segment target approach have been reported for real-time monitoring to high speed objectives with weak radiation flux in harsh environments.
Abstract: We report on high-performance solar-blind photodetectors fabricated on the m-plane $\alpha $ -Ga2O3 epilayer grown by laser molecular beam epitaxy using the segment target approach. Benefited from the improved epitaxial quality with an $\alpha $ -(Al0.24Ga0.76)2O3 intermediate layer, the $\alpha $ -Ga2O3 detector shows a low dark current of 0.23 pA, a UV/visible rejection ratio of over $10^{{5}}$ , a photo-to-dark-current ratio of ${4.4}\times {10}^{{7}}$ , a peak responsivity of 132.6 A/W, a short response time of 97 $\mu \text{s}$ , and a specific detectivity of ${1.23}\times {10}^{{15}}$ Jones at the bias of 10 V. High-temperature operation robustness is also demonstrated up to 423 K, exhibiting the reduction of dark current, a maintained high responsivity (33.9 A/W) and a speedy response (90 $\mu \text{s}$ ), which is on the frontier among the state-of-the-art Ga2O3 solar-blind detectors with a record-high responsivity-bandwidth product. The temperature-dependent transient photocurrent feature implies that high gains result from the enhanced carrier lifetime due to the surface bending. It suggests that the m-plane $\alpha $ -Ga2O3 detectors are promising for real-time monitoring to high-speed objectives with weak radiation flux in harsh environments.
TL;DR: In this article, the authors systematically study the performance limits of sub-10 nm (6.4-9.6 nm) monolayer (ML) AsP TFETs by means of ab initio quantum transport calculation.
TL;DR: In this article , the majority surface states induced by the dry etching of β-Ga2O3 and optimized surface treatments to suppress these electrically active defects with the improved performance of Schottky barrier diodes were identified.
Abstract: Surface treatment after dry etching is vital to enhance the surface quality of the material and thus improve device performance. In this Letter, we identified the majority surface states induced by the dry etching of β-Ga2O3 and optimized surface treatments to suppress these electrically active defects with the improved performance of Schottky barrier diodes. Transient spectroscopies suggested that the majority traps (EC-0.75 eV) related to divacancies (VGa-VO) were enhanced in the concentration of 3.37 × 1014 cm-3 by dry etching and reduced to 0.90 × 1014 cm-3 by the combined means of oxygen annealing and piranha solution treatment. The trap evolution is supported by the suppressed donor-acceptor pair radiative recombination related to oxygen vacancies, the improved carrier transport (negligible hysteresis current-voltage and unity ideality factor), and the reduced surface band bending. These findings provide a straightforward strategy to improve surface quality for the further performance improvement of Ga2O3 power diodes.
TL;DR: In this article , a 1 and 3 wt% Silica-based bioglass (BG) with superior biological performance has been introduced into HA bioceramic to overcome this insufficiency; however, the composite Bioceramics are usually prepared by traditional mechanical mixture of HA and BG powders which tremendously weakens their mechanical performance.
Abstract: Although hydroxyapatite (HA) bioceramic has excellent biocompatibility and osteoconductivity, its high chemical stability results in slow degradation which affects osteogenesis, angiogenesis and clinical applications. Silica-based bioglass (BG) with superior biological performance has been introduced into HA bioceramic to overcome this insufficiency; however, the composite bioceramics are usually prepared by traditional mechanical mixture of HA and BG powders, which tremendously weakens their mechanical performance. In this research, BG-modified HA bioceramics were prepared by the use of BG sol encapsulated HA powders. The results showed that introducing 1 and 3 wt% BG allowed the HA-based bioceramics to maintain the high compressive strength (>300 MPa), improved the apatite mineralization activity, and played an important role in cellular response. The bioceramic modified with 1 wt% BG (1BG/HA) remarkably enhanced in vitro cell proliferation, osteogenic and angiogenic activities. This present work provides a new strategy to improve the biological performance of bioceramics and the HA-based bioceramics with 1 wt% BG can be as a promising candidate material for bone repair.
TL;DR: In this article, the authors demonstrated the NiOx/β-Ga2O3 heterojunction with reduced reverse current and on-resistance via F plasma pre-treatment.
TL;DR: In this paper , the breakdown characteristics of a gate HEMT with a high breakdown voltage of 1205 V and a low specific ON-resistance of 2.22 have been demonstrated.
Abstract: In this letter, we demonstrated a normally-off AlGaN/GaN HEMT using p-NiO as a gate stack combined with a recess structure. The fabricated HEMT exhibits a positive threshold voltage of 1.73 V, a saturation output current of 524 mA/mm, a small subthreshold swing of 79.7 mV/dec and a maximum transconductance as high as 143 mS/mm. This is the first time to demonstrate the breakdown characteristics of a p-NiO gate HEMT with a high breakdown voltage of 1205 V and a low specific ON-resistance of 2.22 $\text{m}\Omega \cdot $ cm2, yielding a competitive Baliga’s figure-of-merit of 0.65 GW/cm2. The instability evaluation of ${V}_{\text {TH}}$ by step stress and pulse transfer curves shows that the p-NiO gate HEMT has a negligible ${V}_{\text {TH}}$ shift in the entire measured gate bias range, which can be attributed to the counteraction between the electron trapping-induced positive $\text{V}_{\text {TH}}$ shift and hole accumulation induced-negative ${V}_{\text {TH}}$ shift. It is well understood in terms of the carrier transport model based on the large band discontinuity at the interface of the p-NiO/AlGaN type-II heterojunction, which is further verified by transient gate current spectra.
TL;DR: Wang et al. as discussed by the authors compared poorly crystalline hydroxyapatite (HA) with different Ca/P molar ratios (1.50, 1.60 and 1.67).
TL;DR: In this paper , the dislocation propagations and reactions in α-Ga2O3 micropillar arrays selectively grown by halide vapor phase epitaxy technique were investigated and the average dislocation density was reduced to 5.3
Abstract: Epitaxial lateral overgrowth (ELO) is an effective strategy to achieve metastable phased α-Ga2O3 with low dislocation densities, which is desirable for developing ultralow-loss and ultrahigh power devices, whereas the involved dislocation dynamics have not been fully exploited. In this Letter, we investigated the dislocation propagations and reactions in α-Ga2O3 micropillar arrays selectively grown by halide vapor phase epitaxy technique. Screw dislocations in α-Ga2O3 micropillars grown from the selective area epitaxy (SAE) to ELO mode exhibited an independent character with an average density of 4.5 × 106 cm−2 while the edge dislocation density was reduced to 5.3 × 108 cm−2. During the initial SAE process, the α-Ga2O3 hexagonal pyramid is developed with the observed inversion domains within the pillar cores. The successive epitaxial lateral overgrowth ELO facilitates the formation of inclined facets upon the SiO2 mask. Almost complete filtering of the underlying threading dislocation has been demonstrated in the ELO wings. Strong image forces induced by inclined free surfaces drive the propagation and reaction of threading dislocations until annihilation, which is well described by the dislocation-filtering model during the dynamic geometry transition of micropillars. These findings may pave the way for the success of the heteroepitaxy of low dislocation density α-Ga2O3 toward the development of high-performance power devices.
TL;DR: In this article , a novel full-color display based on blue Micro LED, which has patterned red and green QDs color conversion (QDCC) layers fabricated by inkjet printing (IJP).
Abstract: Abstract With the ever-growing demands for larger size and high resolution displays, Micro-light-emitting diode (Micro-LED) display with quantum dots (QDs) film as color conversion layers (CCLs) has become one of the most promising candidates of future display for its advantages in low power consumption and wide color range. In this study, we report a novel full-color display based on blue Micro LED, which has patterned red and green QDs color conversion (QDCC) layers fabricated by inkjet printing (IJP). A structure of double-layer bank was designed to reduce color deviation, prevent crosstalk, and flatten the QDCC layer. By optimizing the thickness of the red/green QDCC layers and the wavelength of blue Micro LED backlights, a full-color QDCC-LED display with 228 PPI resolution and size of 1.11-inch was successfully fabricated and showed superb performance. We not only effectively reduced crosstalk, but also improved the color conversion efficiency of QDs. In addition, this QDCC-LED display prepared by embedded bonding process shows a color gamut of 107.53% NTSC. Graphical Abstract
07 Jul 2022
TL;DR: In this paper , a Si-doped κ-Ga2O3 epilayer grown by hydride vapor phase epitaxy was constructed on the high-quality Si-Doped λ-Ga 2O3 Epilayer of a metal-semiconductor-metal (MSM) structure for solar blind photodetectors.
Abstract: The metal-semiconductor-metal (MSM) structure is a popular architecture for developing Ga2O3 solar blind photodetectors. The nature of metal-semiconductor contact is decisive for the operation mode, gain mechanism and device performances. In this contribution, κ-Ga2O3 MSM solar-blind photodetectors with Ti/Ga2O3 Ohmic and Ni/Ga2O3 Schottky contacts were constructed on the high-quality Si-doped κ-Ga2O3 epilayer grown by hydride vapor phase epitaxy. The Ti/κ-Ga2O3/Ti Ohmic MSM device is operated in a photoconductive mode, exhibiting a maximum responsivity of 322.5 A W−1 and a high rejection ratio of over 105, but with an undesirable sub-gap response and high dark current. In comparison, the Ni/Ga2O3/Ni photodiode with a back-to-back Schottky configuration is operated in a mixed photovoltaic and photoconductive mode, demonstrating a decent photoresponsivity of 0.37 A W−1, a maintained high rejection ratio of 1.16 × 105, a detectivity of 3.51 × 1013 Jones and the elimination of slow photoresponse from sub-gap states. The frequency-dependent photoresponse and transient photocurrent characteristics indicate that the persistent photoconductivity effect is responsible for the high gain achieved in the Ti/Ga2O3/Ti photoconductor, and the dominant slow transient decay component is a fingerprint of photoexcited carrier trapping and repopulation. The response speed is improved in the Ni/Ga2O3/Ni Schottky MSM device, whereas carrier transport across interdigitated fingers is affected by bulk traps, limiting the overall response-bandwidth merit.
TL;DR: Li et al. as discussed by the authors showed that the Li2Mg2(PO4)2 bioceramic scaffolds efficiently promoted bone regeneration of critical-size calvarial defects in rats.
Abstract: Both magnesium and lithium are able to stimulate osteogenic and angiogenic activities. In this study, lithium magnesium phosphate (Li0.5Mg2.75(PO4)2, Li1Mg2.5(PO4)2 and Li2Mg2(PO4)2) biomaterials were synthesized by a solid-state reaction method, and their bioceramic blocks and scaffolds were fabricated by compression molding and 3D printing, respectively. The results indicated that the lithium magnesium phosphates consisted of the Mg3(PO4)2 phase and/or LiMgPO4 phase. Compared with the lithium-free Mg3(PO4)2 bioceramics, the lithium magnesium phosphate bioceramics showed a lower porosity and consequently a higher compressive strength, and stimulated in vitro cellular proliferation, osteogenic differentiation and proangiogenic activity. In vivo results manifested that the Li2Mg2(PO4)2 bioceramic scaffolds efficiently promoted bone regeneration of critical-size calvarial defects in rats. Benefiting from the high compressive strength and capacity of stimulating osteogenesis and angiogenesis, the Li2Mg2(PO4)2 bioceramic scaffolds are considered promising for efficiently repairing the bone defects.
TL;DR: In this paper , a bioactive surface modification of tetragonal zirconia polycrystal (Y-TZP) ceramics with outstanding mechanical properties and aesthetic origins are used in dental implant applications.
Abstract: Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramics with outstanding mechanical properties and aesthetic origins are expected to be used in dental implant applications. However, tetragonal zirconia ceramics are not bioactive, which affect the osseointegration and reliability as dental implant materials. Herein, in this study, Y-TZP ceramics were modified by grain-boundary activation via coating a bioactive glass (BG) sol with different content on the crystal surfaces of zirconia powder and followed by being gelled, dried, granulated, low-temperature treated, molded and sintered at 1450°C for 3 h in air. The effects of BG content on the morphology, phase compositions, mechanical properties, in vitro mineralization ability and cell biological properties of the bioactivity modified Y-TZP ceramics were evaluated. The BG additive did not affect the tetragonal–monoclinic phase transformation of ZrO2. However, the addition of BG decreased the flexural strength of the modified Y-TZP ceramics compared to that of Y-TZP. The in vitro mineralization results showed that a homogeneous apatite layer was produced on the surface of the Y-TZP ceramics when they were immersed in the simulated body fluid for 21 days. The cell response results indicated that the bioactive surface modification of Y-TZP ceramics could promote cell adhesion, propagation and osteogenic differentiation performance. Thus, our research results suggest that the highly bioactive Y-TZP ceramics could be a potential candidate for dental implant material.
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TL;DR: In this article , a 9-mm Schottky barrier diodes (SBDs) with a thin-body thickness of 70 µm were used for high-power applications.
Abstract: In this letter, we report 9-mm2 Ga2O3 Schottky barrier diodes (SBDs) with a thin-body thickness of 70 $\mu \text{m}$ . By implementing substrate thinning strategy and dual field plate structures, the resultant device exhibits a high forward current of 20 A, a low differential on-resistance of 57 $\text{m}\Omega $ , a small subthreshold slope of 65 mV/dec and a decent breakdown voltage of 355 V. In particular, a robust electrothermal ruggedness is achieved, including a low junction-to-case thermal resistance of 1.48 K/W and a high surge current of 59 A. Such superior performance is further validated by performing 150-W system-level power factor correction circuit measurements, delivering a record-high conversion efficiency of 98.9%. These results reveal the promise of die-level structure thermal management of the Ga2O3 SBDs for high-power applications.
TL;DR: Based on a metal-oxide-semiconductor (MOS) structure, a double Schottky barrier junction (SBJ) made of NiO/graphene/4H-SiC is built and employed in ultraviolet (UV) detection as discussed by the authors .
Abstract: Based on a metal-oxide-semiconductor (MOS) structure, a double Schottky barrier junction (SBJ) made of NiO/graphene/4H-SiC is built and employed in ultraviolet (UV) detection. The hole concentration of NiO can be modulated as depleted or accumulated states with gate voltages, which allows the device to work in dual-mode when used as a photodetector. In this work, a negative gate bias causes the device to operate as a photoconductive detector with gain due to the negligible Schottky barrier, whereas a zero or positive gate bias makes it work as a Schottky photodiode. The device has a high responsivity of 103.3 A/W and a gain of 490.8 despite the low light intensity (261 nm laser @ 30.19 μW/cm2) at VDS = 5 V and VGS = −3 V. The NiO layer and SiC substrate both serve as UV absorption materials and produce photogenerated carriers, and the device has a wide UV response range from 240 to 400 nm with a gain of 80.34 when VDS = −3 V and VGS = 0 V at 240 nm. The above findings suggest that this MOS-based NiO/graphene/4H-SiC double SBJ has a great prospect in practical UV detection.
TL;DR: In this paper, the authors report on the enhanced radio frequency (RF) performance in sub-micrometer scaled β-Ga2O3 tri-gate FinFETs.
Abstract: In this Letter, we report on the enhanced radio frequency (RF) performance in sub-micrometer scaled β-Ga2O3 tri-gate FinFETs. With a 200-nm-thick β-Ga2O3 bulk channel and a 0.35 μm gate length, the FinFETs exhibit an improved current-gain cutoff frequency of 5.4 GHz and a maximum oscillation frequency of 11.4 GHz, which are 20% and 58% improved with respect to the planar counterpart, respectively. The improved RF performance results from the enhanced gate control capability and the suppressed short-channel effects, as evidenced by the improved pinch-off characteristics, the improved transconductance, and the suppressed output conductance. It suggests that the tri-gate multi-fin architecture is a promising strategy to break the scaling limitation of the gate-channel aspect ratio toward high-performance β-Ga2O3 RF MOSFETs.
TL;DR: In this article , the authors investigated the correlation of carrier transport, trapping and recombination kinetics in NiO/β-Ga2O3 p+-n heterojunction power diodes and showed that the modified Shockley-Read-Hall recombination mediated by majority carrier trap states with an activation energy of 0.64 eV dominates the trap-assisted tunneling process in the forward subthreshold conduction regime.
Abstract: The construction of p-NiO/n-Ga2O3 heterojunction becomes a popular alternative to overcome the technological bottleneck of p-type Ga2O3 for developing bipolar power devices for practical applications, whereas the identification of performance-limiting traps and the bipolar transport dynamics are still not exploited yet. To this end, the fundamental correlation of carrier transport, trapping and recombination kinetics in NiO/β-Ga2O3 p+-n heterojunction power diodes has been investigated. The quantitative modeling of the temperature-dependent current-voltage characteristics indicates that the modified Shockley-Read-Hall recombination mediated by majority carrier trap states with an activation energy of 0.64 eV dominates the trap-assisted tunneling process in the forward subthreshold conduction regime, while the minority carrier diffusion with near-unity ideality factors is overwhelming at the bias over the turn-on voltage. The leakage mechanism at high reverse biases is governed by the Poole-Frenkel emissions through the β-Ga2O3 bulk traps with a barrier height of 0.75 eV, which is supported by the identification of majority bulk traps with the energy level of EC − 0.75 eV through the isothermal capacitance transient spectroscopic analysis. These findings bridge the knowledge gap between bipolar charge transport and deep-level trap behaviors in Ga2O3, which is crucial to understand the reliability of Ga2O3 bipolar power rectifiers.
TL;DR: In this paper , the pH sensing performance of the novel two-dimensional electronic gas (2DEG) at the LaAlO3/SrTiO3 heterostructure interface was investigated.