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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • Dual Material Gate (DMG)
  • Vertical TFET
  • Single Material Gate(SMG)
  • Band-to-band tunneling (BTBT)
应用领域
  • Electronic Science and Technology
机构单位
  • National Institute of Technology Silchar
154 条数据
?? 中文（中国） ▾

  • Solar cell based on vertical graphene nano hills directly grown on silicon

    摘要： We demonstrate a solar cell application based on vertical graphene nano hills (VGNH) directly grown without using a catalyst. The photovoltaic device based on VGNH grown on top of interfacial layer Al2O3 is compared with that on top of bare silicon by critically analyzing its electrical properties. The role of the interfacial layer is to minimize surface recombination and enhance its built-in potential. Our key process is simple to fabricate large-area devices, avoiding an unreliable transfer process. In addition, the thickness of VGNH is optimized and the surface texturing of silicon is performed to overcome the crucial problem of the high reflectivity of silicon. A low reflectivity of thick layers of VGNH is achieved with low series resistance despite of the vertical structure, which is beneficial for high photocurrent. A higher work function of VGNH ~ 4.7 eV is measured by KPFM. The conversion efficiency of 10.97% is achieved with an active area of 0.9 cm2 by co-doping with PEDOT: PSS and inorganic acid HNO3. Moreover, the photo-responsivity of the VGNH-based device is estimated as 1.196 AW-1 under deep ultraviolet light.

    关键词： vertical graphene,graphene doping,graphene nano hills,directly grown graphene,solar cell,anti-reflecting coating,Schottky junction

    更新于2025-09-23 15:21:01

  • Controlled crystallinity and morphologies of 2D Ruddlesden-Popper perovskite films grown without anti-solvent for solar cells

    摘要： Two-dimensional (2D) Ruddlesden-Popper (RP) perovskite films have attracted considerable attention for the environmentally stable perovskite solar cells. However, there is a big space for improving the film crystallinity and its crystallographic orientation to enhance the efficiency of solar cells. In addition, the assistance of anti-solvent is commonly used to obtain a better crystallinity and orientation of 2D RP perovskite films. Nevertheless, the anti-solvent method produces a lot of volatile organic compounds toxic to human health and is challenging to control. Here, we prepared 2D RP perovskite (PEA)2(MA)4Pb5I16 (n = 5) films with the assistance of methylammonium chloride (MACl) additive via a simple one-step deposition method by avoiding anti-solvent treatment. The MACl additive is believed to induce the formation of an intermediate phase composed of perovskite crystals without annealing, which directly promotes the vertical alignment of 2D RP perovskite films on the substrate. The 2D RP films deposited on the mesoporous TiO2 electron transport layer showed high crystallinity and preferential vertical crystallographic orientation. The resulting devices exhibited a power conversion efficiency of 9.7%, much higher than that of the devices prepared without MACl (0.66%).

    关键词： High efficiency,High crystallinity and preferential vertical orientation,Two-dimensional perovskite solar cells,No anti-solvent treatment,MACl additive

    更新于2025-09-23 15:21:01

  • Role of Sb on the vertical-alignment of type-II strain-coupled InAs/GaAsSb multi quantum dots structures

    摘要： The implementation of GaAs0.8Sb0.2 as CL to obtain type-II strain-coupled InAs MQD structures has been examined and compared to similar structures without Sb or without strain coupling. First, it has been demonstrated that capping with GaAsSb prevents the formation of In-rich agglomerations that hampered the QD formation as it has been observed in the sample without Sb. Instead, it promotes the vertical alignment (VA) of almost all QDs with a high density of QD columns. Second, there is a preferential Sb accumulation over the dots together with an undulation of the growth front, contrary to the observed in the uncoupled structure. In case of a deficient covering of GaAsSb, as occurs for giant QDs, In-rich agglomerations may develop. Each VAQD column consists of a sequence of alternating quantum blocks of pyramid-shaped In(Ga)As separated by GaAsSb blocks that rest over them. These Sb-rich blocks are not homogeneous accumulating around the pyramidal apex like a collar. Between the columns, there is an impoverishment of In and Sb compared to the uncoupled sample. These columns can behave as self-aligned nanowires with type II band alignment between self-assembled InAs and GaAsSb quantum blocks that opens new opportunities for novel devices.

    关键词： GaAsSb capping layer,III-V semiconductors alloys,Transmission electron microscopy,Composition distribution,Vertical aligned quantum dots

    更新于2025-09-23 15:21:01

  • Vertical Hyperreflective Lesions on Optical Coherence Tomography in Vitreoretinal Lymphoma

    摘要： IMPORTANCE Vitreoretinal lymphoma is a diagnostic challenge and the pathophysiology is still unclear. OBJECTIVE To describe an imaging finding seen on optical coherence tomography (OCT) of patients with vitreoretinal lymphoma. DESIGN, SETTING, AND PARTICIPANTS This case series study was a retrospective medical record review of patients who received a diagnosis of vitreoretinal lymphoma at the Department of Ophthalmology at Northwestern University between July 2014 and January 2016. MAIN OUTCOMES AND MEASURES Optical coherence tomography findings in vitreoretinal lymphoma. RESULTS We identified 7 patients (4 women [57.1%]; mean [range] age, 62.4 [45-75] years; 12 eyes) with intraocular lymphoma involving the retina (5 patients [71.4%] with primary vitreoretinal or central nervous system lymphoma with ocular involvement, 1 patient [14.3%] with testicular lymphoma with secondary central nervous system lymphoma and vitreoretinal lymphoma, and 1 patient [14.3%] with secondary vitreoretinal lymphoma). We identified vertical hyperreflective lesions that showed moderate or high reflectivity and affected all layers of the neuroretina in 5 patients (7 of 12 eyes [58.3%]). These often preceded the development of subretinal pigment epithelial deposits and were often localized around second-order and third-order retinal vessels. In most cases, they resolved with minimal or no scarring after the initiation of chemotherapy. CONCLUSIONS AND RELEVANCE Vertical hyperreflective lesions are a common physical finding on OCT in eyes with vitreoretinal lymphoma.

    关键词： optical coherence tomography,vertical hyperreflective lesions,vitreoretinal lymphoma

    更新于2025-09-23 15:21:01

  • [IEEE 2018 Second International Conference on Computing Methodologies and Communication (ICCMC) - Erode (2018.2.15-2018.2.16)] 2018 Second International Conference on Computing Methodologies and Communication (ICCMC) - Optimization of N+ hetero pocket doped Dual metal Vertical TFET

    摘要： In this paper, an N+ hetero pocket doped Dual metal Vertical TFET is proposed. Due to an additional tunneling contribution to current along the body thickness of the device the proposed device offers larger ON current and steeper subthreshold slope (SS) as compare to conventional Tunnel FET. Here, the n+ pocket doping is incorporated near the gate source overlap region. Moreover, the pocket material is optimized with different bandgap materials. The dual metal gate (DMG) is used and compared with single material gate (SMG). Further, with an n+ layer at the p-source side, improvements in the device performance in terms of on-current (10-3A), subthreshold swing, SS (39mV/dec) are achieved. The proposed device is optimized for channel length, silicon body layer thickness, source doping engineering, gate dielectric material. Finally, the analog performance of the device is examined and found the device is suitable for high frequency application.

    关键词： Dual Material Gate (DMG),Vertical TFET,Single Material Gate(SMG),Band-to-band tunneling (BTBT)

    更新于2025-09-23 15:21:01

  • Discrete-Pulsed Current Time Method to Estimate Channel Thermal Resistance of GaN-Based Power Devices

    摘要： A simple electrical method to extract device channel thermal resistance in transistors is presented here. The method compares the dc to discrete-pulsed characteristics and estimates the effective increase in channel temperature under dc biasing conditions. Using the discrete-pulsed I versus t method, the self-heating of the device is effectively eliminated, which helps avoiding the underestimation of the device channel thermal resistance, therefore, making it possible to perform thermal measurements at the high power operation. This technique was applied to lateral GaN HEMTs with three different substrates as well as vertical GaN current aperture vertical electron transistor (CAVET) on sapphire, which proved its sensitivity and validity for different device structures and geometries.

    关键词： high-electron mobility transistors (HEMTs),self-heating,current aperture vertical electron transistor (CAVET),Channel thermal resistance

    更新于2025-09-23 15:21:01

  • Numerical Implementation of Wavelength-Dependent Photonic Spike Timing Dependent Plasticity Based on VCSOA

    摘要： We propose to realize photonic spike timing dependent plasticity (STDP) by using a vertical-cavity semiconductor optical amplifier (VCSOA) subject to dual optical pulse injections. The computational model of the photonic STDP is presented for the first time based on the well-known Fabry–Pérot approach. Through numerical simulations, the dependences of photonic STDP on the bias current of VCSOA and the input powers are analyzed carefully. Besides, the effect of the initial wavelength detuning on the photonic STDP is also explored. It is found that, the current scheme requires much lower bias current and input power to obtain controllable STDP curve when compared with the previously reported photonic STDP circuits; the initial wavelength detuning is an effectively controllable parameter to realize wavelength-dependent photonic STDP. The computational model of the photonic STDP based on a VCSOA is interesting and valuable for numerically simulating of large-scale photonic spiking neural network, and provides a guideline to design low power consumption photonic neuromorphic systems.

    关键词： dual optical pulse injections,Vertical-cavity semiconductor optical amplifier,photonic neuromorphic systems,photonic spike timing dependent plasticity,lower power consumption

    更新于2025-09-23 15:21:01

  • Large organic cation incorporation induces vertical orientation growth of Sn-based perovskites for high efficiency solar cells

    摘要： The potential toxic issue of lead content is still a problem for prohibiting the commercialization of lead halide perovskite solar cells (PSCs). as an element of group 14 metals, tin (Sn) is the most likely substitute for lead element in perovskites. However, Sn-based PSCs still suffer from the low power conversion efficiency (PCE) because Sn2+ in tin-based perovskites is easily oxidized into Sn4+ once exposed to air. To fabricate stable and efficient Sn-based PSCs, herein we incorporate large ethylammonium (EA+) cation into CH3NH3SnI3 (MASnI3) abided by the Goldschmidt tolerance factor to fabricate vertically oriented 2D/3D mixed perovskite films. The vertically oriented structure provides a direct pathway for electron and hole transport. As a result, the PCE is highly improved to 9.24% and the corresponding PSC still retains 95% of the initial efficiency after being kept for 30 days without encapsulation in the glovebox. Therefore, our results suggest a promising strategy to develop highly efficient and stable Sn-based PSCs.

    关键词： high efficiency solar cells,Sn-based perovskites,vertical orientation growth,stability,ethylammonium incorporation

    更新于2025-09-23 15:19:57

  • Numerical optimisation and recombination effects on the vertical-tunnel-junction (VTJ) GaAs solar cell up to 10,000 suns

    摘要： Ultra-high concentrator photovoltaic systems (UHCPV), usually referred to CPV systems exceeding 1000 suns, are signalled as one of the most promising research avenues to produce a new generation of high-efficiency and low-cost CPV systems. However, the structure of current concentrator solar cells prevents their development due to the unavoidable series resistance losses at such elevated concentration ratios. In this work, we investigate the performance of the so-called vertical-tunnel-junction (VTJ), recently introduced by the authors, by using advance TCAD. In particular, we carry out an optimisation procedure of the key parameters that affect its performance and conduct a deep investigation of the impact of the main recombination mechanisms and of sun concentration up to 10,000 suns. The results indicate that the performance of the novel structure is not significantly affected by these two factors. A record efficiency of 32.2% at 10,000 suns has been found. This represents a promising way to obtain state-of-the-art efficiencies above 30% for single-band-gap cells, and offers a new route towards the development of competitive CPV systems operating at ultra-high concentration fluxes.

    关键词： Tunnel diode,Concentrator photovoltaics,Vertical solar cells,Series resistance,Gallium arsenide (GaAs)

    更新于2025-09-23 15:19:57

  • CVD preparation of vertical graphene nanowalls/VO2 (B) composite films with superior thermal sensitivity in uncooled infrared detector

    摘要： Vanadium dioxide with superior thermal sensitivity is one of the most preferred materials used in microbolometer, and the B phase of VO2 is particularly prominent. However, conventional VO2 (B) undergoes low temperature-coefficient of resistance (TCR) values and large resistances. In this paper, simple controllable composite films of vertical graphene nanowalls/VO2 (B) (i.e., VGNWs/VO2 (B)) with a suitable square resistance (12.98 k?) and a better temperature-coefficient of resistance (TCR) (-3.2 %/K) were prepared via low pressure chemical vapor deposition. The VGNWs can provide a fast channel for electron transport and enhance the conductivity of VO2 (B). This preparation method can provide a low cost, facile and simple pathway for the design and fabrication of high performance VO2 (B) thin films with superior electrical properties for its application in uncooled infrared detectors.

    关键词： Chemical vapor deposition,VO2 (B) films,Vertical graphene nanowalls,Uncooled infrared detectors

    更新于2025-09-23 15:19:57