The dependence of the substrate resistance, R[subscript sub], for MOS transistor RF modeling on transistor biasing and layout is studied from device simulations and measurements. Though R[subscript sub] is found to be bias dependent, the error incurred by assuming a constant value equal to the DC resistance is not significant....
The purpose of this work is to develop a new model for LDD
n-MOSFET degradation in drain current under long-term AC use
conditions for lifetime projection which includes a self-limiting
effect in the hot-electron induced device degradation.
Experimental results on LDD n-channel MOSFETs shows that the
maximum drain current degradation...
Hot carrier effects in sub-micron lightly doped drain (LDD) n-channel
MOSFETs under static (DC) stress are studied in order to establish the degradation
mechanisms of such devices. Degradation is monitored as a function of time at various
gate voltages. Under accelerated aging conditions (i.e. large drain voltages) the gate
voltage...
High-accuracy and high-speed CMOS track-and-hold (T/H) or sample-and-hold (S/H) circuits are an important part of the analog-to-digital interface. The switched-capacitor (SC) circuits usually contain one or more op-amps whose dc offset, finite gain, finite bandwidth have a big impact on the accuracy of the track-and-hold circuit. Basic correlated double sampling...
Full integration of CMOS low noise amplifiers (LNA) presents a challenge for low
cost CMOS receiver systems. A critical problem faced in the design of an RF CMOS LNA
is the inaccurate high-frequency noise model of the MOSFET implemented in circuit
simulators such as SPICE. Silicon-based monolithic inductors are another...
Reliability of sub-micron analog circuits is directly related to impact ionization and
the subsequent changes in threshold voltage and drain current of n-MOSFET devices.
This thesis presents theory of the hot-electron effects on the device characteristics and
circuit performance, explores several approaches to improve performance at both the
device and...
The major limiting factor of DRAM access time is the low transconductance of the
MOSFET's which have only limited current drive capability. The bipolar junction
transistor(BJT) has a collector current amplification factor, β, times base current and is
limited mostly by the willingness to supply this base current. This collector...
The output characteristics of a conventional GaAs depletion-mode MESFET device have been investigated. One of the important parameters of the small-signal GaAs MESFET model, g[subscript ds] (output conductance), is shown to be frequency and temperature dependent. Variations in g[subscript ds] are a serious problem in many analog and digital circuits...
The long-term goal of this research project is the development of solution-based inorganic dielectric and semiconductor materials for inkjet printed electronics. The main focus of this thesis involves testing of the materials and devices under development. A new solution-based inorganic dielectric material (HfOSO₄), given the name hafsox, is developed and...
GaAs MESFETs are widely used in high speed integrated circuits (ICs) and
microwave circuits. Due to the materials and processing methods used in GaAs
MESFET fabrication, deep level traps in the substrate materials have a strong influence
on device performance.
In this work we used the drain current transient characterization...
The characteristic of the subthreshold current in a
GaAs MESFET exhibits a negative exponential function with
Vgs. After studying the behavior of this current in this
region over a range of temperature and drain bias voltages,
a subthreshold current model was developed. The model was
implemented in a circuit simulation...
A complete Gallium Arsenide Metal Semiconconductor
Field Effect Transistor (GaAs MESFET) model including deep-level
trap effects has been developed, which is far more
accurate than previous equivalent circuit models, for high-speed
applications in linear integrated circuit design.
A new self-backgating GaAs MESFET model, which can
simulate low frequency anomalies, is...
The semiconductor gallium arsenide (GaAs) has many potential
advantages over the more widely used semiconductor silicon (Si).
These include higher low field mobility, semi-insulating substrates,
a direct band-gap, and greater radiation hardness. All these
advantages offer distinct opportunities for implementation of new
circuit functions or extension of the operating conditions...
High speed photodetectors are a necessary element in
broad band digital and analog optical communication systems.
In this thesis easily integrable planar high speed
photodetectors made on undoped semi-insulating (SI) GaAs
substrates are modeled and tested. The fabrication process
of the detectors is fully compatible with GaAs
metal-semiconductor field effect...
The low thermal conductivity of gallium arsenide compared to silicon
results in self-heating effects in GaAs MESFETs that limit the electrical
performance of such devices for high power applications. To date, analytical
thermal models of self heating in GaAs MESFETs are based on the assumption
of a uniformly heated channel....
The focus of this thesis is the investigation of thin-film transistors (TFTs) based on amorphous oxide semiconductors (AOSs) in two circuit applications. To date, circuits implemented with AOS-based TFTs have been primarily enhancement-enhancement inverters, ring oscillators based on these inverters operating at peak frequencies up to ~400 kHz, and two-transistor...
The properties of linear active coupled lines consisting of
electrically long GaAs MESFET structures are investigated for possible
applications as traveling-wave broad-band amplifiers. In addition,
the nonlinear coupled Schottky lines are studied for applications as
voltage tunable circuit elements.
The analysis of the general active asymmetric coupled transmission
lines in...
A class of inorganic thin-film transistor (TFT) semiconductor materials has emerged involving oxides composed of post-transitional cations with (n-1)d¹⁰ns⁰ (n≥4) electronic configurations. This thesis is devoted to the pursuit of topics involving the development of these materials for TFT applications: Deposition of zinc oxide and zinc tin oxide semiconductor
layers...
The parallelization and vectorization of Monte Carlo algorithms for modelling
charge transport in semiconductor devices are considered. The standard ensemble
Monte Carlo simulation of a three parabolic band model for GaAs is first
presented as partial verification of the simulation. The model includes scattering
due to acoustic, polar-optical and intervalley...
This dissertation is an exploration of the material response to Terahertz (THz) radiation. Specifically we will explore the ultrafast electron dynamics in the nonperturbative regime in semiconductors that have been patterned with nanoantenna arrays using broadband, high intensity, THz radiation. Three main semiconductor materials will be studied in this work....