Simulation of hot carriers in semiconductor devices

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (p. 109-113).by Khalid Rahmat.Ph.D

Simulation of hot carriers in semiconductor devices

Includes bibliographical references (p. 109-113).Supported by the U.S. Navy. N00174-93-C-0035Khalid Rahmat

Transport models and advanced numerical simulation of silicon-germanium heterojunction bipolar transistors

Applications in the emerging high-frequency markets for millimeter wave applications more and more use SiGe components for cost reasons. To support the technology effort, a reliable TCAD platform is required. The main issue in the simulation of scaled devices is related to the limitations of the physical models used to describe charge carrier transport. Inherent approximations in the HD formalism are discussed over different technology nodes, providing for the first time a complete survey of HD models capability and restrictions with scaling for simulation of SiGe HBTs. Moreover, a complete set of models for transport parameters of SiGe HBTs is reported, including low-field mobility, energy relaxation time, saturation velocity, high-field mobility and effective density of state. Implementation in a commercial device simulator is drawn and findings are compared with simulation results obtained using a standard set of models and with trustworthy results (i.e. MC and SHE simulation results and experimental data), validating proposed models and clarifying their reliability and accuracy over different technologies. Finally, electrical breakdown phenomena in SiGe HBTs are analyzed: a novel complete model for multiplication factor is reported and validated by experimental results; new M model provides an exhaustive accuracy over a wide range of collector voltages

Macroscopic modeling of quantum effects in semiconductor devices

This dissertation explores the use of macroscopic quantum hydrodynamic (QHD) models as tools for investigating the transport of charge carriers in semiconductor devices in the regime where quantum effects are important. Chapter 1 provides a panoramic view of the field of carrier transport modeling in semiconductors. The essential differences between classical and quantum transport is brought out and a brief outline is given of the derivation of successively less detailed models from the fundamental starting points of the Boltzmann transport equation (BTE) for classical transport and the quantum distribution function (Wigner function, density matrix) based methods for quantum transport. A mention is made of the various quantum hydrodynamic models without going into the details of their derivation and applicability. Chapter 2 brings into focus the area of quantum hydrodynamic modeling of carrier transport. A detailed derivation using the method of moments is presented for each of the popular quantum hydrodynamic models currently being explored in the literature, namely the density-gradient method and the smooth quantum potential model. A summary is made of their limitations and these limitations are then shown as arising out of particular assumptions made in their derivations that could hamper their applicable regimes. Chapter 3 presents an analysis of the boundary layers near interfaces obtained in density-gradient theory. An integral equation for the density near such interfaces is obtained and this is used to analytically compare the DG solution with the solutions from one-electron quantum mechanics in non-degenerate conditions. Confinement in simple potential wells is then discussed using the macroscopic equations. Chapter 4 discusses the derivation of macroscopic equations to describe quantum mechanical tunneling through large barrier potentials. Using the approximate solutions of the Schr?dinger equation it is analytically shown that the density profile inside the barrier satisfies a second order differential equation, very similar to the Schr?dinger equation for a carrier at a suitably chosen average energy. Use of this is made to derive a consistent macroscopic treatment of tunneling transport in the insulating barrier. Chapter 5, the final chapter, summarizes the major contributions of this dissertation and concludes it with several suggestions for future research directions that can stem from this work

Towards a Universal Hot Carrier Degradation Model for SiGe HBTs Subjected to Electrical Stress

The objective of this work is to develop a generalizable understanding of the degradation mechanisms present in complementary Silicon-Germanium (SiGe) heterojunction bipolar transistors (HBTs) that can be used to not only predict the reliable lifetime of these devices but also overcome some of these aging limitations using clever device engineering. This broad motivation for understanding and improving SiGe HBT device reliability is explored through the following specific goals: 1) develop an understanding of the dominant hot carrier degradation sources across temperature (25 K – 573 K); 2) develop a broad understanding of all potentially vulnerable regions of damage within a SiGe HBT using electrically measured data, and how these degradations can be captured in a modeling framework; and 3) design optimized SiGe HBTs that can potentially overcome some of these device-level limitations in reliability across temperature. Being able to simulate the electrical degradation of a complex circuit with SiGe HBTs swinging dynamically on the output plane using a universal physics-based aging model is invaluable for any circuit designer optimizing for high performance and reliability.Ph.D

The Ionospheric Continuous-wave E-region Bistatic Experimental Auroral Radar (ICEBEAR)

The Sun drives many atmospheric processes on Earth through solar electromagnetic radiation, the solar wind, and the solar magnetic field. These solar phenomena interact with a region around the Earth where plasma can be formed, the ionosphere. This region is located 60–1000 km above the surface of the Earth, and is of interest to many scientists and engineers due to the interaction between radio waves and plasma. Variations in the ionospheric plasma density can cause disruptions to GPS signals and radio communications. Attempts have been made to measure the ionospheric plasma properties through the use of rockets, satellites, and remote sensing instrumentation. One of the issues with measuring the ionosphere, specifically the lower altitudes of the ionosphere, is that it is expensive to do in situ. Rockets are required for in situ measurements at altitudes of 90–150 km (the E-region of the ionosphere). Rocket launches are expensive, so more efficient remote methods of measuring the E-region are typically used. This includes radars utilizing radio waves to scatter from the ionospheric plasma. From the scattered signal, plasma properties can be derived to provide insight into the physical processes occurring. The Ionospheric Continuous-wave E-region Bistatic Experimental Auroral Radar (ICEBEAR) was developed to probe the E-region of the ionosphere using this mechanism. Through the use of modern radar hardware and techniques, it was possible to obtain simultaneously high temporal (down to 0.1 s) and spatial (≈ 1.5 km) resolution images of ionospheric plasma density perturbations over a 600 km × 600 km field of view. The radar operates at 49.5 MHz and transmits a continuous-wave, pseudo random noise, phase modulated code to obtain these images. The radar is bistatic, with both transmitter and receiver being located in Saskatchewan, Canada, and operated by the University of Saskatchewan. The radar was designed with future improvements in mind, where each transmitter and receiver antenna are individually controlled/sampled. This Ph.D. dissertation describes the dynamics of the ionosphere, the design and construction of ICEBEAR, and presents some preliminary results, exhibiting the exciting modern capabilities of the system

Journal of Telecommunications and Information Technology, 2004, nr 1

kwartalni

Advances in Solid State Circuit Technologies

This book brings together contributions from experts in the fields to describe the current status of important topics in solid-state circuit technologies. It consists of 20 chapters which are grouped under the following categories: general information, circuits and devices, materials, and characterization techniques. These chapters have been written by renowned experts in the respective fields making this book valuable to the integrated circuits and materials science communities. It is intended for a diverse readership including electrical engineers and material scientists in the industry and academic institutions. Readers will be able to familiarize themselves with the latest technologies in the various fields

Computational and Numerical Simulations

Computational and Numerical Simulations is an edited book including 20 chapters. Book handles the recent research devoted to numerical simulations of physical and engineering systems. It presents both new theories and their applications, showing bridge between theoretical investigations and possibility to apply them by engineers of different branches of science. Numerical simulations play a key role in both theoretical and application oriented research

The 1st International Conference on Computational Engineering and Intelligent Systems

Computational engineering, artificial intelligence and smart systems constitute a hot multidisciplinary topic contrasting computer science, engineering and applied mathematics that created a variety of fascinating intelligent systems. Computational engineering encloses fundamental engineering and science blended with the advanced knowledge of mathematics, algorithms and computer languages. It is concerned with the modeling and simulation of complex systems and data processing methods. Computing and artificial intelligence lead to smart systems that are advanced machines designed to fulfill certain specifications. This proceedings book is a collection of papers presented at the first International Conference on Computational Engineering and Intelligent Systems (ICCEIS2021), held online in the period December 10-12, 2021. The collection offers a wide scope of engineering topics, including smart grids, intelligent control, artificial intelligence, optimization, microelectronics and telecommunication systems. The contributions included in this book are of high quality, present details concerning the topics in a succinct way, and can be used as excellent reference and support for readers regarding the field of computational engineering, artificial intelligence and smart system