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A novel GaN-based lateral SBD with a TUG-AlGaN/GaN heterojunction
摘要： In this study, a novel GaN-based lateral Schottky barrier diode (SBD) with a thin upward graded AlGaN (TUG-AlGaN) barrier layer is proposed and investigated. The TUG-AlGaN layer upward graded from 0 to 0.50 mole fraction is used to replace the thick AlGaN layer of the heterojunction, which can reduce the distance from the 2-D electron gas (2DEG) to the Anode electrode, retain high density of 2DEG near the heterojunction, and eliminate the abrupt AlGaN/GaN conduction band offset at same time, subsequently can reduce the turn-on voltage and on-state voltage. The simulated results show that compared with the conventional SBD (with 25 nm Al0.23Ga0.77N layer), the proposed SBD achieves 0.32V reduction in turn-on voltage, and 1.21V reduction in on-state voltage. Meanwhile, although the proposed SBD doesn’t deliver obvious improvement in static characteristics when compared with the GaN-Based lateral field-effect rectifier (L-FER) (with 25 nm Al0.23Ga0.77N layer), the reverse recovery time of the proposed SBD is much smaller than that of the L-FER (with 25 nm Al0.23Ga0.77N layer). The outstanding static characteristics combined with excellent switching characteristics reveal its great potential for future power applications.
关键词： turn-on voltage,switching characteristics,thin upward graded AlGaN barrier layer,GaN-based lateral Schottky barrier diode
更新于2025-09-23 15:22:29
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Effect of tantalum content on the structural properties and sensing performance of YbTaxOy electrolyte-insulator-semiconductor pH sensors
摘要： In this work, we developed YbTaxOy sensing membranes displaying super-Nernstian pH-sensitivity for use in electrolyte-insulator-semiconductor (EIS) pH sensors. We examined the effect of tantalum content on the structural properties and sensing characteristics of the YbTaxOy sensing membranes deposited through reactive co-sputtering onto Si substrates. X-ray diffraction, atomic force microscopy, secondary ion mass spectrometry, and X-ray photoelectron spectroscopy revealed the structural, morphological, depth, and chemical features, respectively, of these YbTaxOy films prepared under various Ta plasma power conditions (from 80 to 160 W). Among the tested systems, the YbTaxOy EIS device prepared at the 120 W condition exhibited the super-Nernstian sensitivity (70.24 mV/pH), the lowest hysteresis voltage (1.5 mV), and the lowest drift rate (0.26 mV/h). Presumably, this condition optimized the stoichiometry of YbTaO4 in the film and its surface roughness while reducing the crystal defect and suppressing silicate formation at the YbTaxOy-Si interface. The super-Nernstian pH-sensitivity may be attributed to the incorporation of Ta ions in the Yb2O3 forming a YbTaO4 stoichiometric film, enhancing a change in oxidation state of Yb from trivalent ion to bivalent ion and thus transferring one electron to two protons in the redox reaction.
关键词： Electrolyte-insulator-semiconductor (EIS),Sensing characteristics,Plasma power,pH sensitivity,YbTaxOy
更新于2025-09-23 15:22:29
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An In-Depth Study on Electrical and Hydrogen Sensing Characteristics of ZnO Thin Film with Radio Frequency Sputtered Gold Schottky Contacts
摘要： Electrical and hydrogen sensing characteristics of radio frequency sputtered Au/ZnO thin film Schottky diodes on n-silicon substrate have been investigated over a wide temperature range. Current-voltage characterizations of the device in the temperature range of 25°C to 200°C confirm its excellent rectifying property with forward to reverse current ratio of 1610 at an external bias of 5 V. Ideality factor in the range of 4.12 to 2.98 is obtained for Au/ZnO Schottky diode in the aforementioned temperature range, at atmospheric conditions. On exposing diode to hydrogen, a reduction in ideality factor is observed which makes thermionic emission more prominent. The proposed device has proven to be hydrogen sensitive, on account of the lateral shift observed in I ? V characteristics at different hydrogen concentrations (50 ppm-1000 ppm). Maximum barrier height variation of 99 meV and sensitivity of 144% have been observed at 1000 ppm hydrogen at 200°C. A Detailed perusal of the steady-state reaction kinetics of the sensor using I ? V characteristics affirmed that the atomistic hydrogen adsorption at Au/ZnO interface is accountable for the barrier height modulation. The studied sensor depicts remarkable performance for high-temperature detection.
关键词： Hydrogen sensing,Zinc oxide (ZnO) thin film,Electrical characteristics,Schottky diode,Metal-semiconductor interface,Palladium catalyst
更新于2025-09-23 15:22:29
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Deposition of ZnS thin films by electron beam evaporation technique, effect of thickness on the crystallographic and optical properties
摘要： Deposition of Zinc sulfide (ZnS) thin films on Si (100) and glass substrates has been performed using electron beam evaporation (EBE) method without annealing. Film structure has been analyzed by XRD, while SEM and AFM have been used to explore the films morphology. Raman spectroscopy has been used to confirm film composition. The stoichiometry has been verified by EDX and XPS techniques. XRD patterns indicated that the films possess a polycrystalline cubic structure with orientations along (111) and (220) planes. The crystallinity has been better with film thickness in the 350–1700 nm range while the RMS roughness increases. Optical properties of the grown films were characterized by optical transmittance measurements (UV–Vis). The deduced energy band gap of the films shows a clear reduction from 3.45 eV to 3.36 eV with increasing film thickness. The evolution of refractive index, extinction coefficient, and dielectric constants with thickness has been investigated from transmittance spectra in the 500–1000 nm wavelength range.
关键词： ZnS,optical characteristics,Thin films,electron beam evaporation
更新于2025-09-23 15:22:29
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Determining Series Resistance for Equivalent Circuit Models of a PV Module
摘要： Literature describes various methods for determining a series resistance for a photovoltaic device from measured IV curves. We investigate use of these techniques to estimate the series resistance parameter for a single diode equivalent circuit model. With simulated IV curves we demonstrate that the series resistance values obtained by these techniques differ systematically from the known series resistance parameter values used to generate the curves, indicating that these methods are not suitable for determining the series resistance parameter for the single diode model equation. We present an alternative method to determine the series resistance parameter jointly with the other parameters for the single diode model equation, and demonstrate the accuracy and reliability of this technique in the presence of measurement errors.
关键词： Current-voltage characteristics,parameter extraction,electric resistance,solar panels
更新于2025-09-23 15:22:29
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[IEEE 2018 China International SAR Symposium (CISS) - Shanghai (2018.10.10-2018.10.12)] 2018 China International SAR Symposium (CISS) - A Fast Target Detection Method for SAR Image Based on Electromagnetic Characteristics
摘要： Target detection for remote sensing images which contain optical images and radar images has attracted lots of relative researchers. With the development of deep learning, target detection for optical images has been developing towards high accuracy and real-time detection. High resolution optical images reflect geometric features of the object. Unlike optical images, SAR images reflect the electromagnetic characteristics of the target, so the SAR image detection which uses optical image detection algorithm will lead to weak detection performance. This paper studies a fast target detection algorithm for SAR images which fused electromagnetic characteristics and geometric features through support vector machine. The algorithm is based on the Faster R-CNN framework enabling nearly cost-free target detection.
关键词： real-time detection,scattering center model,electromagnetic characteristics,Faster R-CNN,target detection
更新于2025-09-23 15:22:29
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Analysis of current transport mechanisms in sol-gel grown Si/ZnO heterojunction diodes in high temperature environment
摘要： This paper analyzes the electrical parameters of Si/ZnO heterojunction diodes in the wide temperature range, i.e. from room temperature (298 K) to 573 K to study the electrical performance of the diode in very high temperature environment. In this work, sol-gel derived nanostructured ZnO thin film was deposited directly on p-Si substrate using spin coating technique. Electrical parameters, such as rectification ratio, reverse saturation current, ideality factor, barrier height, series resistance and activation energy are derived from current-voltage characteristics of the device, measured using semiconductor parameter analyzer in the temperature range of 298 K–573 K for bias voltage of ± 5 V. The ideality factor, barrier height and series resistance is derived as 2.66, 0.789 eV and 3554 Ω respectively at 298 K, whereas at 573 K these are modified as 1.58, 1.15 eV and 801 Ω respectively. The above-mentioned results indicate the presence of spatial barrier height inhomogeneities (BHI) in high temperature environment. Hence, we have included the Gaussian distribution of spatial BHI in our analysis to calculate the effective Richardson constant (RC). Before inclusion of spatial BHI, RC was 4.026 × 10^{-6} Acm^{-2}K^{-2}. However, after inclusion of spatial BHI, RC is modified to 29.14 Acm^{-2}K^{-2}, which is nearer to the theoretical value (32 Acm^{-2}K^{-2}). Therefore, this study indicates that our as-fabricated Si/ZnO heterojunction diodes can sustain their electrical behaviour in very high temperature environment also and they are suitable for high temperature electronic and optoelectronic application.
关键词： Current-voltage characteristics,Richardson constant,Trap-assisted tunneling,Spatial barrier inhomogeneities,Heterojunction diode,Semiconductor thin film
更新于2025-09-23 15:22:29
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Band bending analysis of charge characteristics at GeO <sub/>2</sub> /Ge interface by x-ray photoemission spectroscopy
摘要： Ge complementary metal oxide semiconductor (CMOS) is promising for scaling beyond the Si CMOS due to its higher carrier mobility than Si. Analogue to classical SiO2/Si system in the Si CMOS technology, various interface/bulk charges including interface traps (Qit), fixed surface state charges (Qf), trapped positive charges (Qpt) and negative charges ((Qnt) in GeO2/Ge system are also crucial both for the device performance and reliability. Because small amounts of charges would cause photoemission peak shift characterized by x-ray photoemission spectroscopy (XPS), it offers a feasible way to evaluate various charge densities by measuring the band bending in Ge substrate from Ge 3d core-level energy shift at GeO2/Ge interface. Moreover, photoemission peak shifts as a function of x-ray irradiation time have been widely accepted for characterization of charge trapping phenomena. Here, we report a band bending analysis at GeO2/Ge interface of featuring vital charge characteristics for diverse device applications by XPS. HF-last cleaned Ge surface was verified to tend to be p-type, irrespective of the bulk conductivity. The n-Ge/GeO2 interfaces exhibit a reduction of upward band bending evolution of Ge substrate, while p-type-Ge/GeO2 interfaces indicate a reduction of downward band bending evolution when comparing the different quality GeO2/Ge interfaces. Based on the requirement of surface charge neutrality, such observation has been attributed to a dominated passivation effect to negatively charged interface traps and the positive fixed surface state charges, respectively. Moreover, a time evolution of Ge 3d and O 1s signals reveals a progressive band bending modification at GeO2/Ge interface, clarifying the thermally-grown GeO2 also contains electron traps (Qnt). Ultimately, the four types of charges relying on the GeO2/Ge quality were modeled to correlate with the observed Ge band bending evolution, which would impact both the device operation and reliability.
关键词： band bending,x-ray photoemission spectroscopy,Ge-based electronics,charge characteristics
更新于2025-09-23 15:22:29
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DC and RF characteristics optimization of AlGaN/GaN/BGaN/GaN/Si HEMT for microwave-power and high temperature application
摘要： AlGaN/GaN/Si high electron mobility transistors (HEMTs) developed by molecular beam epitaxy (MBE) are studied with several methods for characterization, the most utilized are direct-current and radio-frequency measurements, to see power and microwave performance of components. The increase in these parameters is not based just with on improvement technological for example, decrease of length gate (Lg) and passivation. For sure, another very important point is to reduce the thickness of barrier while keeping the reduction in the length of gate, in order to reduce the transit time (τ), and consequently access to highest cut-o? frequency (FT). For this situation, it’s appears a harmful phenomenon of type “punch-through”, because of the weak con?nement of electrons in the channel. In this paper, the main objective is to show how to reduce this e?ect.
关键词： HEMT GaN,Radio-frequency,Current-voltage characteristics,RF characteristics,Alloys BGaN
更新于2025-09-23 15:21:21
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Effects of material degradation on electrical and optical characteristics of surface dielectric barrier discharge
摘要： In this paper, screen-printed electrodes are asymmetrically fabricated on three different dielectrics (multi-layered polyimide, quartz, and alumina). Supplied with AC power, sustainable surface dielectric barrier discharge (SDBD) plasma is generated in atmospheric pressure. During plasma processing, different changes of material degradation and discharge images are observed. The corresponding electrical and optical characteristics are investigated by optical emission spectra (OES) and Lissajous figure analysis, respectively. It is found that both dielectric degradation and electrode erosion occur on the surface of the polyimide based SDBD device, while there is only electrode erosion for the quartz and alumina based devices, which results in different changes of electrical characteristics. OES calculated results show that with an increase of discharge aging time, electron temperature increases for the polyimide based SDBD device and decreases for quartz and alumina based SDBD devices, while all the gas temperatures of three dielectrics increase with the aging time. Furthermore, compared to vibrational temperature and gas temperature, the distribution of electron temperature is more suitable for evaluating the changes in discharge uniformity during plasma processing.
关键词： electrical characteristics,plasma processing,optical characteristics,surface dielectric barrier discharge,material degradation
更新于2025-09-23 15:21:21