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

A PLL Design Based on a Standing Wave Resonant Oscillator

In this thesis, we present a new continuously variable high frequency standing wave oscillator and demonstrate its use in generating the phase locked clock signal of a digital IC. The ring based standing wave resonant oscillator is implemented with a plurality of wires connected in a mobius configuration, with a cross coupled inverter pair connected across the wires. The oscillation frequency can be modulated by coarse and fine tuning. Coarse modification is achieved by altering the number of wires in the ring that participate in the oscillation, by driving a digital word to a set of passgates which are connected to each wire in the ring. Fine tuning of the oscillation frequency is achieved by varying the body bias voltage of both the PMOS transistors in the cross coupled inverter pair which sustains the oscillations in the resonant ring. We validated our PLL design in a 90nm process technology. 3D parasitic RLCs for our oscillator ring were extracted with skin effect accounted for. Our PLL provides a frequency locking range from 6 GHz to 9 GHz, with a center frequency of 7.5 GHz. The oscillator alone consumes about 25 mW of power, and the complete PLL consumes a power of 28.5 mW. The observed jitter of the PLL is 2.56 percent. These numbers are significant improvements over the prior art in standing wave based PLLs

Investigation and suppression of semiconductor–oxide related defect states : from surface science to device tests

Many present challenges in semiconductor technology are related to utilizing solid structures with atomic scale dimensions and materials with higher charge carrier mobility and/or other readily controllable properties. These include many surface-related problems because the ratio of surface parts of devices to the whole material volume increases all the time in practical device structures. One of the major problems has been oxidation of semiconductor surfaces during the manufacturing of devices. This PhD work deals with the surface and oxide interface properties of different III–V semiconductors induced by the oxidation, the study of which is imperative in realizing devices with desired characteristics. The general goal has been in finding answers to these problematic issues on atomic scale, and whether they can be resolved with simple parameter control of a thermal oxidation treatment. Much of the work leans on a previous novel finding of crystalline oxide phases on indium-containing III–V semiconductor (100) surfaces. Various aspects of applicability of such a structure in real semiconductor devices are considered in this work. Common denominator in all of the experiments and studies is that the initial investigations were carried out in very controlled environment in ultrahigh-vacuum: detailed basics and initial characterizations were carried out with high resolution and precision surface science methods. In particular, this work has resulted in novel crystalline oxide phases observed on GaSb(100) and InSb(111)B semiconductor surfaces. They have been extensively discussed from an applied point of view as well as their fundamental characteristics, relating to their already previously studied counterpart, InSb(100). Furthermore, beneficial passivating characteristics of a stabilizing crystalline InOx interfacial layer beneath an Al2O3 and reasons behind such behavior are demonstrated for InGaAs IR detector device structure. This thesis provides background of semiconductors, their surfaces, interfaces, and semiconductor technology as appropriate, research methods utilized, and briefly summarizes the findings of the work

Modelling of field-effect transistors based on 2D materials targeting high-frequency applications

New technologies are necessary for the unprecedented expansion of connectivity and communications in the modern technological society. The specific needs of wireless communication systems in 5G and beyond, as well as devices for the future deployment of Internet of Things has caused that the International Technology Roadmap for Semiconductors, which is the strategic planning document of the semiconductor industry, considered since 2011, graphene and related materials (GRMs) as promising candidates for the future of electronics. Graphene, a one-atom-thick of carbon, is a promising material for high-frequency applications due to its intrinsic superior carrier mobility and very high saturation velocity. These exceptional carrier transport properties suggest that GRM-based field-effect transistors could potentially outperform other technologies. This thesis presents a body of work on the modelling, performance prediction and simulation of GRM-based field-effect transistors and circuits. The main goal of this work is to provide models and tools to ease the following issues: (i) gaining technological control of single layer and bilayer graphene devices and, more generally, devices based on 2D materials, (ii) assessment of radio-frequency (RF) performance and microwave stability, (iii) benchmarking against other existing technologies, (iv) providing guidance for device and circuit design, (v) simulation of circuits formed by GRM-based transistors.Comment: Thesis, 164 pages, http://hdl.handle.net/10803/40531

Millimeter-Wave MMICs and Applications

As device technology improves, interest in the millimeter-wave band grows. Wireless communication systems migrate to higher frequencies, millimeter-wave radars and passive sensors find new solid-state implementations that promise improved performance, and entirely new applications in the millimeter-wave band become feasible. The circuit or system designer is faced with a new and unique set of challenges and constraints to deal with in order to use this portion of the spectrum successfully. In particular, the advantages of monolithic integration become increasingly important. This thesis presents many new developments in Monolithic Millimeter-Wave Integrated Circuits (MMICs), both the chips themselves and systems that use them. It begins with an overview of the various applications of millimeter waves, including a discussion of specific projects that the author is involved in and why many of them demand a MMIC implementation. In the subsequent chapters, new MMIC chips are described in detail, as is the role they play in real-world projects. Multi-chip modules are also presented with specific attention given to the practical details of MMIC packaging and multi-chip integration. The thesis concludes with a summary of the works presented thus far and their overall impact on the field of millimeter-wave engineering.</p

3D drift diffusion and 3D Monte Carlo simulation of on-current variability due to random dopants

In this work Random Discrete Dopant induced on-current variations have been studied using the Glasgow 3D atomistic drift/diffusion simulator and Monte Carlo simulations. A methodology for incorporating quantum corrections into self-consistent atomistic Monte Carlo simulations via the density gradient effective potential is presented. Quantum corrections based on the density gradient formalism are used to simultaneously capture quantum confinement effects. The quantum corrections not only capture charge confinement effects, but accurately represent the electron impurity interaction used in previous \textit{ab initio} atomistic MC simulations, showing agreement with bulk mobility simulation. The effect of quantum corrected transport variation in statistical atomistic MC simulation is then investigated using a series of realistic scaled devices nMOSFETs transistors with channel lengths 35 nm, 25 nm, 18nm, 13 nm and 9 nm. Such simulations result in an increased drain current variability when compared with drift diffusion simulation. The comprehensive statistical analysis of drain current variations is presented separately for each scaled transistor. The investigation has shown increased current variation compared with quantum corrected drift diffusion simulation and with previous classical MC results. Furthermore, it has been studied consistently the impact of transport variability due to scattering from random discrete dopants on the on-current variability in realistic nano CMOS transistors. For the first time, a hierarchic simulation strategy to accurately transfer the increased on-current variability obtained from the ‘ab initio’ MC simulations to DD simulations is subsequently presented. The MC corrected DD simulations are used to produce target $I_D-V_G$ characteristics from which statistical compact models are extracted for use in preliminary design kits at the early stage of new technology development. The impact of transport variability on the accuracy of delay simulation are investigated in detail. Accurate compact models extraction methodology transferring results from accurate physical variability simulation into statistical compact models suitable for statistical circuit simulation is presented. In order to examine te size of this effect on circuits Monte Carlo SPICE simulations of inverter were carried out for 100 samples

Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems

We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.Peer ReviewedPostprint (published version

An Investigation of the MBE Growth of InGaAs and InAlAs Lattice Matched to InP

The MBE growth of In0.53Gao.47As and In0.52Al0.48As lattice matched to InP is investigated. Accurate formulae relating the splitting between X-ray rocking curve peaks to the composition of InxGa(1-x)As and InxAl(1-x)As are developed, enabling accurate characterisation of alloy composition close to the lattice matched condition. Close scrutiny of the behaviour of InAs RHEED intensity oscillations indicates that the onset of In droplet formation during InAs growth correlates with a small reduction in the period of the intensity oscillations. This reduction can therefore be used to identify the minimum permissible As2 partial pressure for good morphology growth at any substrate temperature. The measured values of minimum As2 flux for the growth of InAs agree very well with predictions based on simple thermodynamic arguments. These arguments can be extended to deal with the behaviour of In0.53Gao.47As and In0.52Al0.48As by treating the ternary alloys as a pseudo-binary compounds. The results are again in excellent agreement with experimental measurements, although in the case of In0.52Al0.48As it is necessary to derive the necessary thermodynamical constants by performing a fit to the experimental data