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GaN ${p}$ -channel field-effect transistors ( ${p}$ -FETs) are essential components for implementing the energy-efficient complementary logic circuitry for monolithic GaN power integration. This letter reports the threshold voltage ( ${V}_{\mathrm {TH}}$ ) instability of ${p}$ -channel GaN MOSFETs with Al2O3 as the gate dielectric. When the gate-to-source bias sweeps toward the negative direction, the ${V}_{\mathrm {TH}}$ exhibits a shift toward more negative values. The impacts of such ${V}_{\mathrm {TH}}$ instability on GaN complementary logic circuits are characterized using logic inverters and ring oscillators. It is shown that impacts on circuit functions are limited with an operating voltage swing below 5 V. However, the propagation delay could be gradually prolonged, as a result of the drifting ${V}_{\mathrm {TH}}$ .

Owing to its energy efficiency, silicon complementary metal–oxide–semiconductor (CMOS) technology is the current driving force of the integrated circuit industry. Silicon’s narrow bandgap has led to the advancement of wide-bandgap semiconductor materials, such as gallium nitride (GaN), being favoured in power electronics, radiofrequency power amplifiers and harsh environment applications. However, the development of GaN CMOS logic circuits has proved challenging because of the lack of a suitable strategy for integrating n-channel and p-channel field-effect transistors on a single substrate. Here we report the monolithic integration of enhancement-mode n-channel and p-channel GaN field-effect transistors and the fabrication of GaN-based complementary logic integrated circuits. We construct a family of elementary logic gates—including NOT, NAND, NOR and transmission gates—and show that the inverters exhibit rail-to-rail operation, suppressed static power dissipation, high thermal stability and large noise margins. We also demonstrate latch cells and ring oscillators comprising cascading logic inverters. Through the monolithic integration of enhancement-mode n-type and p-type gallium nitride field-effect transistors, complementary integrated circuits including latch circuits and ring oscillators can be created for use in high-power and high-frequency applications.

Carboxymethyl cellulose (CMC) hydrogels have been used as adhesive materials for food and other newly emerged innovative applications. To increase the knowledge of CMC hydrogel-based adhesives and optimize the preparation and storage conditions in practical, we prepared CMC hydrogels for cigar wrapper application and investigated their adhesive performance as affected by different CMC type, concentration, pH, temperature, and storage time, etc. Two parameters, initial adhesiveness and peel strength were used to evaluate the adhesive behavior of CMC with paper and tobacco leaf. Sample C2 with relatively medium molecular weight and medium degree of substitution values showed the best adhesive performance. Hydrogels prepared using boiled water at neutral pH presented better adhesive behavior, which was not significantly affected by storage temperature (up to 13 days). The wettability, steady shear flow behavior, dynamic rheological properties, and stress recovery performance of CMC hydrogel were measured, and their correlations to the adhesive behavior were discussed.

A hybrid field-effect transistor (HyFET), superior for power electronic applications, can be created by harnessing the merits of two representative wide-bandgap semiconductors, gallium nitride (GaN) and silicon carbide (SiC). Yet, the incompactness in the epitaxy techniques hinders the development of the HyFET-GaN is usually grown on on-axis foreign substrates including SiC, whereas SiC homoepitaxy prefers off-axis substrates. This work presents a GaN-based heterostructure epitaxially grown on a conventional 4° off-axis 4H-SiC substrate, which manifests its high quality and suitability for constructing GaN-based high-electron-mobility transistors, thereby suggesting a practical approach to realizing HyFETs. In the meanwhile, a distinct two-step biaxial strain-relaxation process is proposed and studied with comprehensive characterizations.

Summary The static PN junction is the foundation of integrated circuits. Herein, we pioneer a high current density generation by mechanically moving N-type semiconductor over P-type semiconductor, named as the dynamic PN junction. The establishment and destruction of the depletion layer causes the redistribution and rebounding of diffusing carriers by the built-in field, similar to a capacitive charge/discharge process of PN junction capacitance during the movement. Through inserting dielectric layer at the interface of the dynamic PN junction, output voltage can be improved and designed numerically according to the energy level difference between the valence band of semiconductor and conduction band of dielectric layer. Especially, the dynamic MoS2/AlN/Si generator with open-circuit voltage of 5.1 V, short-circuit current density of 112.0 A/m2, power density of 130.0 W/m2, and power-conversion efficiency of 32.5% has been achieved, which can light up light-emitting diode timely and directly. This generator can continuously work for 1 h, demonstrating its great potential applications., Graphical Abstract, Highlights • High current density direct-current generator based on dynamic PN junctions • Dynamic equilibrium between establishment and destruction of the depletion layer • Capacitive discharge of PN junction capacitance caused by hot carriers rebounding • Enhance and design voltage numerically by inserting dielectric layer at the interface, Electrical Engineering; Energy Materials; Mechanical Engineering; Tribology

Natural polysaccharide-based hydrogels are promising in food and pharmaceutical applications. In this study, the potential of composite hydrogels prepared by carboxymethyl cellulose (CMC) and chitosan as glue for cigar wrapping applications was firstly studied. The impacts of degree of carboxymethyl substitution (DS) and the ratio of CMC:chitosan on the adhesive performance and rheological behaviors of composite hydrogels have been investigated. And the results indicated that relatively low DS of CMC and relatively low ratio of chitosan might be favorable for the adhesive properties of composite hydrogels. But a higher ratio of chitosan may significantly improve the rheological properties of composite hydrogels and alter their thermal-sensitivity. The impacts of chitosan on the wet ability with tobacco leaf, the morphology and the XRD patterns of composite hydrogels were also observed. The CMC-chitosan composite hydrogel could significantly decrease the total molds on tobacco leaf brought by CMC, and therefore may show great potential to improve the quality of cigar during long-term storage. All the information in this study is new, which could be useful for exploring the application of CMC-chitosan composite hydrogel in food, pharmaceutical, even other fields.

Summary Although perovskite has been widely explored in optoelectronic devices, it has been rarely explored as a Schottky junction. Here, we demonstrate a light- and mechanical-energy co-harvesting generator based on a dynamic metal/perovskite Schottky junction. In dark conditions, by moving Al over perovskite film (conductivity: 70.0 S/cm), output voltage and current density of −0.70 V and −41.1 A/m2, respectively, are achieved. As defects eliminate the photo-generated carriers in the static metal/perovskite junction under light illumination, the photoresponse is negligible. Strikingly, the output current of dynamic metal/perovskite junction under light illumination is enhanced by 3-fold compared with the dynamic junction in the dark condition. This nonlinear photo-enhanced effect is proposed as a result of strong interaction between the photo-generated and bound back carriers in the dynamic Schottky junction as well as the high light-absorption coefficient of perovskite. A flexible Al/perovskite generator has been demonstrated as a wearable energy-harvesting device.

The realization of p-type conduction in GaN and commercialized GaN light-emitting diodes (LED) is accepted as an advance in the development of human society. Conventionally, LED is based on PN junction and the quantum wells are introduced for confining electrons and holes, which improves the external quantum efficiency (EQE). Herein, we realized a graphene/AlGaN/GaN LED emitting double peaks at 430 nm and 560 nm. The blue peak at 430 nm is originated from the recombination process between holes injected from graphene/AlGaN heterostructure and electron produced from the tunnelling and avalanche multiplication process in p-type AlGaN/p-type GaN interface. Compared with the bare p-type AlGaN/GaN heterostructure without blue light emission, the graphene/p-AlGaN enhances the hole injection process through the band gap alignment and the mediate thickness of p-AlGaN is important taking the hole transport in AlGaN into consideration. The AlGaN/GaN interface confines the produced electrons and thus result in a high EQE of 55.8% under 5 mA current after intercalating an Al2O3 barrier at the interface between graphene and AlGaN/GaN. Moreover, the tunable graphene/AlGaN/GaN LED with different intensity of 430 nm has been demonstrated through changing the Fermi level of graphene by gating effect. The graphene/AlGaN heterostructure induced confinement effect can bring a novel type of LED, which can be optimized for special applications.

A 650-V/84-mΩ normally-off GaN/SiC cascode power device has been developed using a high-voltage (HV) D-mode SiC JFET and a low-voltage (LV) E-mode GaN HEMT. The single-pulse avalanche capability of the GaN-HEMT/SiC-JFET cascode device is investigated using an unclamped inductive switching (UIS) testing setup. A Zener diode in parallel with the LV GaN HEMT is used to eliminate the voltage spikes at the drain terminal of LV GaN HEMT during the switching transients and is found to significantly affect the maximum single-pulse avalanche energy (E AS ). The voltage rating of Zener diode (V z ) determines how the UIS energy is consumed by the high-voltage (HV) GaN/SiC cascode power device during the avalanche breakdown process. With a higher V z of 30V, the UIS energy is fully released by the SiC JFET’s gate-to-drain (D GD ) junction diode in avalanche mode, and the maximum E AS is up to 162.3mJ. With a lower V z of 15V, the channel of SiC JFET can be activated at the beginning of the avalanche process of D GD and undertakes part of UIS energy, facilitating a larger E AS up to 342.7mJ.

The impact ionization induced breakdown and related high-temperature reverse bias (HTRB) behaviors are studied in 100-V Schottky-type p-GaN gate high-electron-mobility transistors (HEMTs). It is revealed that impact ionization is initiated by the electrons injected from the source-side through the buffer layer to the high electric-field (E-field) region. The generated hot electrons, when being captured by surface states, could lead to re-distribution of E-field and delay of breakdown. Meanwhile, holes generated by impact ionization would transport to the region under the gate, and dynamically change the device threshold voltage. Under long-term HTRB stress, the impact ionization is also found to shorten the device lifetime and significantly impact the accuracy of lifetime prediction. Such a phenomenon is weakened at elevated temperatures as a result of the reduced impact ionization rate.

There is a rising prospective in harvesting energy from the environment, as in situ energy is required for the distributed sensors in the interconnected information society, among which the water flow energy is the most potential candidate as a clean and abundant mechanical source. However, for microscale and unordered movement of water, achieving a sustainable direct-current generating device with high output to drive the load element is still challenging, which requires for further exploration. Herein, we propose a dynamic PN water junction generator with moving water sandwiched between two semiconductors, which outputs a sustainable direct-current voltage of 0.3 V and a current of 0.64 μ A. The mechanism can be attributed to the dynamic polarization process of water as moving dielectric medium in the dynamic PN water junction, under the Fermi level difference of two semiconductors. We further demonstrate an encapsulated portable power-generating device with simple structure and continuous direct-current voltage output of 0.11 V, which exhibits its promising potential application in the field of wearable devices and the IoTs.

A 700-V normally-off p-GaN gate HEMT featuring area-efficient distributed built-in Schottky barrier diode (SBD) is demonstrated with low-loss reverse conduction capability. The reverse conduction voltage of the device V RC is - {2.1 V (@ I_D = -20 mA/mm). As the reverse conduction is through the built-in SBD, the low V RC of the proposed transistor is independent of the HEMT's V TH and turn-off gate bias V GS . On the contrary, the V RC of a conventional p-GaN gate power transistor is not only much higher but also strongly dependent on the V TH and OFFstate V GS . The built-in SBD elements are embedded into the HEMT's source side in a distributed fashion along the width of the device, so that the SBD and HEMT share a common access region in forward and reverse conduction, leading to reduced ON-resistance (R ON ) compared to the scheme with side-by-side transistor/SBD pair. The anode of built-in Schottky contact is embedded at the source side and is shielded from the high electric field by the gate field plate. Thus, the reverse leakage current of Schottky contact is well-suppressed.

In this paper, a remote fitting system is proposed for garment e-commerce. The system includes a flexible humanoid robot, an interactive interface, a rotary shooting device and a comfort measuring device. We design a physical fitting robot to simulate body shapes of consumers and replace them to finish the fitting process remotely. The rotary shooting device is designed for taking and processing pictures of fitting results. The comfort measuring device is designed to obtain the pressure values and convert them into comfort information. The processed fitting pictures and comfort information are fed back to the customers as the reference when they buy or customize clothes, which helps to reduce the return rate of online shopping and increase the orders of customized garment. The remote fitting system eliminates the restrictions of geographical location and improves the accuracy of fitting results for garment e-commerce.

A type of broadband (325−980 nm) self-powered photodetector based on graphene/GaAs van der Waals heterojunction is reported. By simply spinning a layer of Ag nano-particles (Ag NPs) onto graphene/GaAs heterostructure, the responsivity and detectivity of our devices for the whole spectrum range are enhanced significantly. The maximum photocurrent responsivity of 210 mA W−1 (increased by 38%) and detectivity of 2.98 × 1013 Jones (increased by 202%) are achieved at 405 nm, which is about two or three orders of magnitude larger than other graphene based self-powered photodetectors. The mechanism of the improvement originates from the overlap the depletion region of graphene/GaAs heterostructure, the surface plasmon enhanced light field region below the surface and the light absorption region of the GaAs layer. The external quantum efficiency (EQE) measurement, transient photoluminescence (PL) test and the comparative theoretical simulation show that the surface plasmon enhancement should only be applicable for graphene/direct band gap semiconductor heterostructure, where the semiconductor should have a high optical absorption coefficient. The obtained high performance broadband photodetector with excellent detectivity is a promising candidate for many important optoelectronic applications, such as ultrasensitive image sensor in charge coupled displayer field, which requires colour sensors not only with high photo responsivity but also in a wide spectral range.

The surface of the p-GaN layer in Schottky-type p-GaN gate high-electron-mobility transistors (HEMTs) can be reinforced with enhanced immunity to hot electron bombardment by reconstructing the surface region of p-GaN into GaON. The surface region of p-GaN is treated by remote oxygen plasma and subsequently annealed at 800 °C, thereby becoming a thin crystalline gallium oxynitride (GaON) layer that will be in direct contact with the Schottky metal. The GaON exhibits a lower valence band maximum energy than that of the p-GaN, which leads to a higher Schottky barrier at the metal/GaON interface to holes and, thus, greatly suppresses the forward gate leakage. More importantly, with higher thermodynamic stability and a larger bandgap of ∼4.1 eV, the GaON reinforces the susceptible metal/p-GaN interface against the hot electrons and, thus, substantially enhances the long-term gate reliability of p-GaN gate HEMTs under forward bias stress. The high-temperature thermal process is indispensable for the surface reconstruction, without which the plasma oxidation only reduces the gate leakage but fails to prolong the time-dependent gate breakdown lifetime.

In this study, soybean protein isolate (SPI) and glucose (glc) were conjugated by wet Maillard reaction at 95 °C for 0–6 h with a mass ratio of 1:2. The degree of grafting and SDS-PAGE of SPI-conjugates were studied and a highest degree of grafting (23.14 %) was achieved at reaction time of 4 h. Gels were then prepared by crosslinking SPI-glc mixture or conjugates using transglutaminase, and their mechanical properties were charactered by hardness and gumminess. To further study the impact of conjugation on the gastrointestinal digestion of gel, rheological properties of gels after in vitro gastric and intestinal digestions were evaluated through amplitude and frequency sweep tests. Compared with SPI and SPI-glc mixture, gels formed by conjugates with 1 h and 4 h reaction time showed significantly higher viscosity, storage modulus (G') and complex modulus (G*) values after gastric digestion, indicating that these conjugate gels had slower gastric digestion kinetics. There were no significant differences among these samples in simulated intestinal digestion. Therefore, the SPI-glc conjugate gels may have great potential to be used for gastric delivery.

As a typical two-dimensional (2D) atomic thin material, the massless Dirac Fermions in graphene promise many unique physical properties, such as high carrier mobility and high light transmission. However, after a decade of research and a huge number of papers focusing on graphene, high performance graphene based optoelectronic devices is still lacked, which should be achieved for realizing competitive industrial graphene product. In this review, we point out high performance optoelectronic devices such as solar cells, photodetector and light emitting diodes can be demonstrated by properly marrying graphene with semiconductor. The fundamental physics of graphene/semiconductor heterostructure as well as its optoelectronic properties are comprehensively addressed. We suggest six strategies of improving the performance of graphene/semiconductor based optoelectronic devices. The outstanding light harvesting enhancement characteristic of surface plasmon is detailed represented to highlight its importance and potential. Especially, we indicate that graphene/semiconductor heterostructure solar cell can reach a power conversion efficiency of 30%.

A viable approach to enhance the photovoltaic performance of graphene (Gr)/semiconductor solar cells has been demonstrated. In order to take full advantage of the solar energy in the range of visible and ultraviolet light, InP and ZnO quantum dots (QDs) with band gaps of 2.4 eV and 3.3 eV, respectively, are simultaneously introduced to dope Gr by a photo-induced doping mechanism. Raman and photoluminescence measurements indicate that the photo-induced holes diffuse into Gr, leading to p-doping of Gr. As a result, the power conversion efficiency (PCE) of the Gr/GaAs heterostructure solar cell with good stability can be improved from 8.57% to 11.50%. Although this process is simple and feasible, we emphasize that the mixed semiconductor QDs enhanced Gr/semiconductor heterostructure solar cell is similar to the band gap engineering of traditional multi-junction bulk semiconductor solar cells.

Photodetectors based on graphene/GaAs heterostructure were fabricated and demonstrated for application in self-powered photodetection. Then, Si quantum dots (QDs) were spin-coated onto the surface of devices to enhance the built-in field by photo-induced doping, because of the tunable Fermi level (EF) of graphene and shallow junction of the heterojunction. Additionally, Au nanoparticles (NPs) working as light trapping structure were used to enhance quantum efficiency of Si QDs and optical absorption of heterojunction, benefitting from localized surface plasmon resonance (LSPR). Therefore, a large-area photodetector under self-powered condition achieved high performance i.e. responsivity (1.81×105 V/W), detectivity (2.0×1012 Jones), fast response speed (

Static heterojunction-based electronic devices have been widely applied because carrier dynamic processes between semiconductors can be designed through band gap engineering. Herein, we demonstrate a tunable direct-current generator based on the dynamic heterojunction, whose mechanism is based on breaking the symmetry of drift and diffusion currents and rebounding hot carrier transport in dynamic heterojunctions. Furthermore, the output voltage can be delicately adjusted and enhanced with the interface energy level engineering of inserting dielectric layers. Under the ultrahigh interface electric field, hot electrons will still transfer across the interface through the tunneling and hopping effect. In particular, the intrinsic anisotropy of black phosphorus arising from the lattice structure produces extraordinary electronic, transport, and mechanical properties exploited in our dynamic heterojunction generator. Herein, the voltage of 6.1 V, current density of 124.0 A/m 2 , power density of 201.0 W/m 2 , and energy-conversion efficiency of 31.4% have been achieved based on the dynamic black phosphorus/AlN/Si heterojunction, which can be used to directly and synchronously light up light-emitting diodes. This direct-current generator has the potential to convert ubiquitous mechanical energy into electric energy and is a promising candidate for novel portable and miniaturized power sources in the in situ energy acquisition field.

In this work, the impact ionization-induced OFF-state breakdown is revealed and systematically investigated in 100 V Schottky-type p-GaN gate high-electron-mobility transistors. Impact ionization is found to occur in the peak electric-field region at the source-terminated field-plate edge and is initiated by electrons injected from the source-side two-dimensional electron gas channel through the buffer layer. Hot electrons generated from impact ionization, when being captured by surface traps, could lead to redistribution and peak value reduction of electric-field. Consequently, the sudden rise in the OFF-state leakage current by impact ionization could be self-clamped temporally to avoid catastrophic rupture of the device. The impact ionization is further verified by the increase in dynamic OFF-state leakage current and a negative shift in threshold voltage, both of which result from positively charged holes (generated from impact ionization) drifting toward the gated channel.

There has been a great interest in utilization of plant protein such as dry edible bean (Phaseolus vulgaris L.) proteins as cost-effective biomaterials to replace animal proteins for delivery of nutrients in foods. The functional properties of bean proteins may be further improved by tuning the degree of enzymatic hydrolysis. In this study, the complexation of Great Northern bean hydrolysates (BPH) with curcumin was investigated. Compared to the micro-sized BPH globulins (1.2–1.5 μm in diameter), self-assembled nanocomplexation took place spontaneously after mixing with curcumin, with size ranging from 244.7 to 344.7 nm. BPH with 5% degree of hydrolysis (DH) showed the highest curcumin loading capacity value (9.97 μg/mg). By investigating the intrinsic fluorescence quenching and curcumin fluorescence enhancement, we found that the binding affinity was increased at low DH but decreased at the DH of 7% or higher, compared to pristine protein. BPH-5 showed the highest loading capacity (9.97 μg/mg), relatively small particle size (286.9 nm) and low PDI value (0.359), and optimal storage stability, which was mainly attributed to its relatively high binding affinity and surface hydrophobicity. The findings in this study provide insight on fabricating, optimizing and selecting plant protein-based delivery systems in functional foods.

Traditionally, Schottky diodes are used statically in the electronic information industry while dynamic or moving Schottky diode-based applications are rarely explored. Herein, a novel Schottky diode named "moving Schottky diode generator" is designed, which can convert mechanical energy into electrical energy by means of lateral movement between the graphene/metal film and semiconductor. The mechanism is based on the built-in electric field separation of the diffusing carriers in moving Schottky diode. A current-density output up of 40.0 A m-2 is achieved through minimizing the contact distance between metal and semiconductor, which is 100-1000 times higher than former piezoelectric and triboelectric nanogenerators. The power density and power conversion efficiency of the heterostructure-based generator can reach 5.25 W m-2 and 20.8%, which can be further enhanced by Schottky junction interface design. Moreover, the graphene film/semiconductor moving Schottky diode-based generator behaves better flexibility and stability, which does not show obvious degradation after 10 000 times of running, indicating its great potential in the usage of portable energy source. This moving Schottky diode direct-current generator can light up a blue light-emitting diode and a flexible graphene wristband is demonstrated for wearable energy source.

The overloaded energy cost has become the main concern of the now fast developing society, which make novel energy devices with high power density of critical importance to the sustainable development of human society. Herein, a dynamic Schottky diode based generator with ultrahigh power density of 1262.0 W m−2 for sliding Fe tip on rough p‐type silicon is reported. Intriguingly, the increased surface states after rough treatment lead to an extremely enhanced current density up to 2.7 × 105 A m−2, as the charged surface states can effectively accelerate the carriers through large atomic electric field, while the reflecting directions are regulated by the built‐in electric field of the Schottky barrier. This research provides an open avenue for utilizing the surface states in semiconductors in a subversive way, which can co‐utilize the atomic electric field and built‐in electric field to harvest energy from the mechanical movements, especially for achieving an ultrahigh current density power source.

By combining the surface plasmon enhancement technique with gating effect, a tunable blue lighting emitting diode (LED) based on graphene/Ag nanoparticles (NPs)-polymethyl methacrylate (PMMA)/graphene/p-GaN heterostructure has been achieved. The surface plasmon enhancement is introduced through spin-coating Ag nanoparticles on graphene/p-GaN heterostructure while the gating effect is demonstrated through a graphene/PMMA/graphene sandwich structure, where the top graphene layer acts as the gate electrode. Compared with initial graphene/p-GaN heterostructure LEDs, the electroluminescence (EL) emission intensity of Ag NPs/graphene/p-GaN heterostructure LEDs has been largely enhanced, attributing to the surface plasmon resonance (SPR) of Ag nanoparticles. The EL emission intensity of graphene/Ag NPs-PMMA/graphene/p-GaN heterostructure LEDs can further be gate-tunable effectively through exerting a static voltage between the sandwich structure, which tunes the Fermi level of graphene contacting with p-GaN. These results indicate that through sophisticated design, graphene/Ag NPs-PMMA/graphene/p-GaN heterostructure LEDs can be a potential candidate for many essential electronic and optoelectronic applications.

2D materials hold great potential for designing novel electronic and optoelectronic devices. However, 2D material can only absorb limited incident light. As a representative 2D semiconductor, monolayer MoS2 can only absorb up to 10% of the incident light in the visible, which is not sufficient to achieve a high optical-to-electrical conversion efficiency. To overcome this shortcoming, a "gap-mode" plasmon-enhanced monolayer MoS2 fluorescent emitter and photodetector is designed by squeezing the light-field into Ag shell-isolated nanoparticles-Au film gap, where the confined electromagnetic field can interact with monolayer MoS2 . With this gap-mode plasmon-enhanced configuration, a 110-fold enhancement of photoluminescence intensity is achieved, exceeding values reached by other plasmon-enhanced MoS2 fluorescent emitters. In addition, a gap-mode plasmon-enhanced monolayer MoS2 photodetector with an 880% enhancement in photocurrent and a responsivity of 287.5 A W-1 is demonstrated, exceeding previously reported plasmon-enhanced monolayer MoS2 photodetectors.