Modelling and Simulations in Electronic and Optoelectronic Engineering

Prediction through modelling forms the basis of engineering design. The computational power at the fingertips of the professional engineer is increasing enormously and techniques for computer simulation are changing rapidly. Engineers need models which relate to their design area and are adaptable to new design concepts. They also need efficient and friendly ways of presenting, viewing and transmitting the data associated with their models. This book collects five chapters and provides a detailed guide for the design and test of electronic and optoelectronic devices allowing engineers to simulate individual devices and electronic circuits and performing a large number of different analyses needed for tasks such as verification of circuit designs and prediction of circuit performance. A particular attention is devoted to scaling of transistors, which in the last half of century has been the driving force for electronics. A wide variety of devices are also being explored to complement or even replace silicon transistors at molecular scales. Similarities between nanoscale and microscale transistors exist, but nanotransistors also behave in drastically different ways. For example, ballistic transport and quantum effects become much more important. Moreover the downscaling of power integrated devices and the increase of the dissipated power density emphasise the importance of a proper thermal analysis during the design process. Particularly in GaAs technology, one of the main problems to overcome is the low thermal conductivity of the semiconductor, which focuses the designer’s interest both on the device layout and package thermal optimization when good reliability is to be achieved. Ideal as a reference for professional engineers or as a text for courses in electronic and optoelectronic device modelling, the proposed book presents: • a combination of background device physics and technology; • a review of existing device models; • a set of new and improved models compatible with the most advanced technology, which I have already proposed in literature during a period of over thirty years of my research activity; • descriptions of device models and examples of circuit simulations. In the first chapter an analytical model to optimize the thermal and electrical layout for multilayer structure electronic devices is reviewed. The model is based on the solution to the non-linear 3-D heat equation. The thermal solution is achieved by the Kirchhoff transform and the 2-D Fourier transform. In the second chapter the authors review a very accurate and fast model of Photonic Band-Gap (PBG) structure characterized by a two-dimensional (2D) periodic change of the refractive index and finite height, therefore named quasi 3D PBG. The model is based on the Floquet-Bloch formalism and allows to find all the propagation characteristics, including the space harmonics and the total field distribution, the propagation constants, the guided and radiated power and modal loss induced by the 2D grating. The third chapter presents a MMIC design technique oriented to the optimization of the production yield. The method, based on a sensitivity analysis, i.e. on the circuit behavior for value variations of passive elements from their nominal value, and on the contemporary determination of the production yields, allows both the identification the circuit elements to obtain high production yield and an appropriate choice of the circuit topology. In the fourth chapter a powerful and efficient model to characterize photonic band-gap structures incorporating multiple defects, having arbitrary shape and dimensions, is reviewed. The model provides to model defects in wave-guiding, finite-size photonic band gap devices and analytical and closed-form expressions for the reflection and transmission coefficients and out-of-plane losses, very useful and easy to be implemented for any operating conditions. The method has been applied to look into the capabilities of wave-guiding photonic band gap devices in DWDM filtering applications. In particular the design of some optical filters has been carried out and optimal design rules have been drawn. Finally, last chapter is devoted to analyze the modelling of Carbon Nanotube Field Effect Transistors directly and easily implementable in simulation software, and many examples of electronic circuit design are reviewed. The authors are with Electronic Device Research Group of Department of Electrical and Electronic Engineering (Polytechnic of Bari, Italy), founded by me on 1987.