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Influences of ALD Al2O3 on the surface band-bending of c-plane, Ga-face GaN and the implication to GaN-collector npn heterojunction bipolar transistors

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arXiv 2021年

作者： Gong, Jiarui Kim, Jisoo Ng, TienKhee Lu, Kuangye Kim, Donghyeok Zhou, Jie Liu, Dong Kim, Jeehwan Ooi, Boon S. Ma, Zhenqiang Department of Physics University of Wisconsin-Madison MadisonWI53706 United States Department of Electrical and Computer Engineering University of Wisconsin-Madison MadisonWI53706 United States Department of Electrical and Computer Engineering King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia Department of Mechanical Engineering Department of Materials Science and Engineering Massachusetts Institute of Technology CambridgeMA02139 United States

Due to the lack of effective p-type doping in GaN and the adverse effects of surface band-bending of GaN on electron transport, developing practical GaN heterojunction bipolar transistors has been impossible. The recently demonstrated approach of grafting n-type GaN with p-type semiconductors, like Si and GaAs, by employing ultrathin (UO) Al2O3 at the interface of Si/GaN and GaAs/GaN, has shown the feasibility to overcome the poor p-type doping challenge of GaN by providing epitaxy-like interface quality. However, the surface band-bending of GaN that could be influenced by the UO Al2O3 has been unknown. In this work, the band-bending of c-plane, Ga-face GaN with UO Al2O3 deposition at the surface of GaN was studied using X-ray photoelectron spectroscopy (XPS). The study shows that the UO Al2O3 can help in suppressing the upward band-bending of the c-plane, Ga-face GaN with a monotonic reduction trend of the upward band-bending energy from 0.48 eV down to 0.12 eV as the number of UO Al2O3 deposition cycles is increased from 0 to 20 cycles. The study further shows that the band-bending can be mostly recovered after removing the Al2O3 layer, concurring that the change in the density of fixed charge at the GaN surface caused by UO Al2O3 is the main reason for the surface band-bending modulation. The potential implication of the surface band-bending results of AlGaAs/GaAs/GaN npn heterojunction bipolar transistor (HBT) was preliminarily studied via Silvaco® simulations. Copyright © 2021, The Authors. All rights reserved.

关键词： X ray photoelectron spectroscopy

Regularity and numerical approximation of fractional elliptic differential equations on compact metric graphs

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arXiv 2023年

作者： Bolin, David Kovács, Mihály Kumar, Vivek Simas, Alexandre B. Statistics Program Computer Electrical and Mathematical Sciences and Engineering Division King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia Department of Mathematical Sciences Chalmers University of Technology University of Gothenburg GothenburgSE-41296 Sweden Department of Differential Equations Budapest University of Technology and Economics Mauegyetem rkp. 3. BudapestH-1111 Hungary Faculty of Information Technology and Bionics Pázmány Péter Catholic University Práter utca 50/a. BudapestH-1083 Hungary Theoretical Statistics and Mathematics Unit Indian Statistical Institute Bangalore Centre 8th Mile Mysore Road Karnataka Bangalore560059 India

The fractional differential equation Lβu = f posed on a compact metric graph is considered, where β > 0 and L = κ2 − ∇(a∇) is a second-order elliptic operator equipped with certain vertex conditions and sufficiently smooth and positive coefficients κ, a. We demonstrate the existence of a unique solution for a general class of vertex conditions and derive the regularity of the solution in the specific case of Kirchhoff vertex conditions. These results are extended to the stochastic setting when f is replaced by Gaussian white noise. For the deterministic and stochastic settings under generalized Kirchhoff vertex conditions, we propose a numerical solution based on a finite element approximation combined with a rational approximation of the fractional power L−β. For the resulting approximation, the strong error is analyzed in the deterministic case, and the strong mean squared error as well as the L2(Γ×Γ)error of the covariance function of the solution are analyzed in the stochastic setting. Explicit rates of convergences are derived for all cases. Numerical experiments for L = κ2 − ∆, κ > 0 are performed to illustrate the *** Codes 35R02, 35A01, 35A02, 60H15, 60H40 Copyright © 2023, The Authors. All rights reserved.

关键词： Errors

Asymptotic and exponential decay in mean square for delay geometric Brownian motion

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arXiv 2020年

作者： Haskovec, Jan Computer Electrical and Mathematical Sciences & Engineering King Abdullah University of Science and Technology Thuwal23955 Saudi Arabia

We derive sufficient conditions for asymptotic and monotone exponential decay in mean square of solutions of the geometric Brownian motion with delay. The conditions are written in terms of the parameters and are explicit for the case of asymptotic decay. For exponential decay, they are easily resolvable numerically. The analytical method is based on construction of a Lyapunov functional (asymptotic decay) and forward-backward estimate for the square mean (exponential decay).MSC Codes 34K11, 34K25, 34K50, 60H10 Copyright © 2020, The Authors. All rights reserved.

关键词： Lyapunov functions

Direct proof of unconditional asymptotic consensus in the Hegselmann-Krause model with transmission-type delay

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arXiv 2020年

作者： Haskovec, Jan Computer Electrical and Mathematical Sciences & Engineering King Abdullah University of Science and Technology Thuwal23955 Saudi Arabia

We present a direct proof of asymptotic consensus in the nonlinear Hegselmann-Krause model with transmission-type delay, where the communication weights depend on the particle distance in phase space. Our approach is based on an explicit estimate of the shrinkage of the group diameter on finite time intervals and avoids the usage of Lyapunov-type functionals or results from nonnegative matrix theory. It works for both the original formulation of the model with communication weights scaled by the number of agents, and the modification with weights normalized a'la Motsch-Tadmor. We pose only minimal assumptions on the model parameters. In particular, we only assume global positivity of the influence function, without imposing any conditions on its decay rate or monotonicity. Moreover, our result holds for any length of the delay. Copyright © 2020, The Authors. All rights reserved.

关键词： Phase space methods

Renewable Biodiesel Production from Oleaginous Yeast Biomass Using Industrial Wastes

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Renewable Biodiesel Production from Oleaginous Yeast Biomass...

2019 Research, Invention, and Innovation Congress, RI2C 2019

作者： Kongruang, Sasithorn Roytrakul, Sittiruk Sriariyanun, Malinee Bioprocess Engineering and Biotechnology Center Department of Biotechnology Faculty of Applied Science King Mongkut's University of Technology North Bangkok Bangkok Thailand Department of Electrical and Computer Engineering Faculty of Engineering King Mongkut' S University of Technology North Bangkok Bangkok Thailand Chemical and Process Engineering Program Sirindhorn International Thai-German Graduate School of Engineering King Mongkut's University of Technology North Bangkok Bangkok Thailand

The accumulation lipid from oleaginous microorganisms is recognized as a second generation fuel. Biooil is known to as intracellular product of oily yeast utilizing various carbon substrates and converting different quantities of lipids in the form of triacylglycerols. This second generation fuel can be used to make biodiesel via a transesterification process. This study investigated the morphological characteristics of eight strains of Thai oleaginous yeasts via microscopy and analyzed the fatty acid profiling of yeasts cultured in three carbon sources: glucose, sugar cane molasses and crude glycerol in order to estimate biodiesel properties. To approach this goal, batch fermentations were used to culture eight yeast strains, Rhodosporidium toruloides TISTR 5123, TISTR 5154, TISTR 5149, Yarrowia lipolytica TISTR 5054, TISTR 5151, TISTR 5621, Rhodotorula glutinis TISTR 5159 and Rhodotorula graminis TISTR 5124 for 96 h under 30°C at 250 rpm. Result revealed that eight yeast strains contained significant amounts of fatty acids and lipids and accumulated mainly palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C 18:1) and linoleic acid (C18:2), and they are suitable for the production of biodiesel. Fatty acid productions and profiles indicated that these yeast strains can be potentially used as the triacylglycerols producers for biodiesel production. © 2020 The Authors, published by EDP sciences.

关键词： Lipids

An Efficient 2D Discrete Cosine Transform Processor for Multimedia Applications

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An Efficient 2D Discrete Cosine Transform Processor for Mult...

IEEE Signal Processing and Communications Applications (SIU)

作者： Hasan Erdem Yantir Ahmed M. Eltawil Khaled N. Salama Computer Electrical and Mathematical Sciences & Engineering (CEMSE) King Abdullah University of Science and Technology Thuwal Saudi Arabia

ISBN: (数字)9781728172064

ISBN: (纸本)9781728172071

The memory bottleneck is the biggest concern affecting the scalability of traditional computer architectures. Furthermore, the necessity of applications to process the huge amount of data is increasing, especially after the evaluation of artificial intelligence (AI). This fact forces researchers to move through the more data-centric architectures rather than the existing processor centric ones. In-memory processors are such architecture that combines the memory and processor in the same location to eliminate the memory bottleneck. Associative processors are an ideal candidate for in-memory computation, especially for signal processing since the data is a key point in these applications. To demonstrate this, 2D DCT is implemented in associate in-memory processors. According to the comparison with the state of the art hardware realization, the proposed accelerator achieves the best energy efficiency for 4K HD inputs at 30 frames per second.

关键词： Discrete cosine transforms Two dimensional displays computer architecture Table lookup Mathematical model Registers Image coding

Reliable High-Frequency Fabricated Fractional-Order Capacitors and Their Passive Circuit Models

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Reliable High-Frequency Fabricated Fractional-Order Capacito...

IEEE Signal Processing and Communications Applications (SIU)

作者： Aslihab Kartci Norbert Herencsar Khaled Nabil Salama Computer Electrical and Mathematical Sciences and Engineering Division King Abdullah University of Science and Technology Thuwal Saudi Arabia

ISBN: (数字)9781728172064

ISBN: (纸本)9781728172071

The impedance characteristics of three different type of fractional-order capacitors (FOCs) with an order of -0.74, -0.79, and -0.91 are analyzed. The used devices have excellent feature such as constant phase angle in the frequency range 10 MHz - 100 MHz. Their impedance data is fitted with second-order passive electrical model structures of Foster-I abd Foster-II using standard EIA-48 compliant component values phase error. The effect on phase and pseudo-capacitance using a detailed experimental study of series-, parallel-, and inter-connected FOCs is also shown.

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Well posedness and asymptotic consensus in the Hegselmann-Krause model with finite speed of information propagation

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arXiv 2020年

作者： Haskovec, Jan Computer Electrical and Mathematical Sciences & Engineering King Abdullah University of Science and Technology Thuwal23955 Saudi Arabia

We consider a variant of the Hegselmann-Krause model of consensus formation where information between agents propagates with a finite speed c. This leads to a system of ordinary differential equations (ODE) with state-dependent delay. Observing that the classical well-posedness theory for ODE systems does not apply, we provide a proof of global existence and uniqueness of solutions of the model. We prove that asymptotic consensus is always reached in the spatially one-dimensional setting of the model, as long as agents travel slower than c. We also provide sufficient conditions for asymptotic consensus in the spatially multi-dimensional *** Codes 34K20, 34K60, 82C22, 92D50 Copyright © 2020, The Authors. All rights reserved.

关键词： Information dissemination

Predicting road traffic density using a machine learning-driven approach

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Predicting road traffic density using a machine learning-dri...

electrical, computer and Energy Technologies (ICECET), International Conference on

作者： Abdelhafid Zeroual Fouzi Harrou Ying Sun Faculty of technology University of 20 August 1955 Skikda Algeria LAIG Laboratory University of 08 May 1945 Guelma Algeria Computer Electrical and Mathematical Sciences and Engineering (CEMSE) Division King Abdullah University of Science and Technology (KAUST) Thuwal Saudi Arabia

ISBN: (纸本)9781665442329

Notwithstanding the technological developments in transportation systems, traffic congestion is still hampering the growth and development of countries. Accurate traffic flow prediction plays an essential role in intelligent transportation systems to mitigate traffic congestion problems. Importantly, it provides prior knowledge on traffic status, which enables avoiding congested points. This paper employed a Support vector regression (SVR) approach, a kernel-based learning model, to predict traffic flow. We assessed the efficiency of the SVR model for traffic density prediction by considering different types of kernels. We used traffic data from California highways to test the SVR prediction performance. Results showed that SVR with Gaussian kernel dominates the other SVR models.

关键词： Support vector machines Roads Linear regression Transportation Machine learning Predictive models Spatiotemporal phenomena