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ASU Electronic Theses and Dissertations


This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.

In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.

Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.


Contributor
Resource Type
  • Doctoral Dissertation
Date Range
2010 2019


High-Resistivity Silicon (HRS) substrates are important for low-loss, high-performance microwave and millimeter wave devices in high-frequency telecommunication systems. The highest resistivity of up to ~10,000 ohm.cm is Float Zone (FZ) grown Si which is produced in small quantities and moderate wafer diameter. The more common Czochralski (CZ) Si can achieve resistivities of around 1000 ohm.cm, but the wafers contain oxygen that can lead to thermal donor formation with donor concentration significantly higher (~1015 cm-3) than the dopant concentration (~1012-1013 cm-3) of such high-resistivity Si leading to resistivity changes and possible type conversion of high-resistivity p-type silicon. In this research capacitance-voltage …

Contributors
Nayak, Pinakpani, Schroder, Dieter K, Vasileska, Dragica, et al.
Created Date
2012

Zinc oxide (ZnO), a naturally n-type semiconductor has been identified as a promising candidate to replace indium tin oxide (ITO) as the transparent electrode in solar cells, because of its wide bandgap (3.37 eV), abundant source materials and suitable refractive index (2.0 at 600 nm). Spray deposition is a convenient and low cost technique for large area and uniform deposition of semiconductor thin films. In particular, it provides an easier way to dope the film by simply adding the dopant precursor into the starting solution. In order to reduce the resistivity of undoped ZnO, many works have been done by …

Contributors
Zhou, Bin, Tao, Meng, Goryll, Michael, et al.
Created Date
2013

In very small electronic devices the alternate capture and emission of carriers at an individual defect site located at the interface of Si:SiO2 of a MOSFET generates discrete switching in the device conductance referred to as a random telegraph signal (RTS) or random telegraph noise (RTN). In this research work, the integration of random defects positioned across the channel at the Si:SiO2 interface from source end to the drain end in the presence of different random dopant distributions are used to conduct Ensemble Monte-Carlo ( EMC ) based numerical simulation of key device performance metrics for 45 nm gate length …

Contributors
Ashraf, Nabil Shovon, Vasileska, Dragica, Schroder, Dieter, et al.
Created Date
2011

Silicon carbide (SiC), long touted as a material that can satisfy the specific property requirements for high temperature and high power applications, was studied quantitatively using various techniques. The electronic band structure of 4H SiC is examined in the first half of this dissertation. A brief introduction to band structure calculations, with particular emphasis on the empirical pseudopotential method, is given as a foundation for the subsequent work. Next, the crystal pseudopotential for 4H SiC is derived in detail, and a novel approach using a genetic algorithm search routine is employed to find the fitting parameters needed to generate the …

Contributors
Ng, Garrick, Schroder, Dieter K, Vasileska, Dragica, et al.
Created Date
2010

High-k dielectrics have been employed in the metal-oxide semiconductor field effect transistors (MOSFETs) since 45 nm technology node. In this MOSFET industry, Moore’s law projects the feature size of MOSFET scales half within every 18 months. Such scaling down theory has not only led to the physical limit of manufacturing but also raised the reliability issues in MOSFETs. After the incorporation of HfO2 based high-k dielectrics, the stacked oxides based gate insulator is facing rather challenging reliability issues due to the vulnerable HfO2 layer, ultra-thin interfacial SiO2 layer, and even messy interface between SiO2 and HfO2. Bias temperature instabilities (BTI), …

Contributors
Fang, Runchen, Barnaby, Hugh J, Kozicki, Michael N, et al.
Created Date
2018

This dissertation aims to demonstrate a new approach to fabricating solar cells for spectrum-splitting photovoltaic systems with the potential to reduce their cost and complexity of manufacturing, called Monolithically Integrated Laterally Arrayed Multiple Band gap (MILAMB) solar cells. Single crystal semiconductor alloy nanowire (NW) ensembles are grown with the alloy composition and band gap changing continuously across a broad range over the surface of a single substrate in a single, inexpensive growth step by the Dual-Gradient Method. The nanowire ensembles then serve as the absorbing materials in a set of solar cells for spectrum-splitting photovoltaic systems. Preliminary design and simulation …

Contributors
Caselli, Derek, Ning, Cun-Zheng, Tao, Meng, et al.
Created Date
2014

In this thesis, the methods of aluminum electroplating in an ionic liquid for silicon solar cell front side metallization were studied. It focused on replacing the current silver screen printing with an alternative metallization technology using a low-cost Earth-abundant metal for mass production, due to the high cost and limited availability of silver. A conventional aluminum electroplating method was employed for silicon solar cells fabrication on both p-type and n-type substrates. The highest efficiency of 17.9% was achieved in the n-type solar cell with a rear junction, which is comparable to that of the same structure cell with screen printed …

Contributors
Wang, Laidong, Tao, Meng, Vasileska, Dragica, et al.
Created Date
2018

To date, the most popular and dominant material for commercial solar cells is crystalline silicon (or wafer-Si). It has the highest cell efficiency and cell lifetime out of all commercial solar cells. Although the potential of crystalline-Si solar cells in supplying energy demands is enormous, their future growth will likely be constrained by two major bottlenecks. The first is the high electricity input to produce crystalline-Si solar cells and modules, and the second is the limited supply of silver (Ag) reserves. These bottlenecks prevent crystalline-Si solar cells from reaching terawatt-scale deployment, which means the electricity produced by crystalline-Si solar cells …

Contributors
Sun, Wen-Cheng, Tao, Meng, Vasileska, Dragica, et al.
Created Date
2016

In this work, transport in nanowire materials and nanowire field effect transistors is studied using a full band Monte Carlo simulator within the tight binding basis. Chapter 1 is dedicated to the importance of nanowires and nanoscale devices in present day electronics and the necessity to use a computationally efficient tool to simulate transport in these devices. Chapter 2 discusses the calculation of the full band structure of nanowires based on an atomistic tight binding approach, particularly noting the use of the exact same tight binding parameters for bulk band structures as well as the nanowire band structures. Chapter 3 …

Contributors
Hathwar, Raghuraj, Goodnick, Stephen M, Goodnick, Stephen M, et al.
Created Date
2016

High-performance III-V semiconductors based on ternary alloys and superlattice systems are fabricated, studied, and compared for infrared optoelectronic applications. InAsBi is a ternary alloy near the GaSb lattice constant that is not as thoroughly investigated as other III-V alloys and that is challenging to produce as Bi has a tendency to surface segregate and form droplets during growth rather than incorporate. A growth window is identified within which high-quality droplet-free bulk InAsBi is produced and Bi mole fractions up to 6.4% are obtained. Photoluminescence with high internal quantum efficiency is observed from InAs/InAsBi quantum wells. The high structural and optical …

Contributors
Webster, Preston Thomas, Johnson, Shane R, Zhang, Yong-Hang, et al.
Created Date
2016

A primary motivation of research in photovoltaic technology is to obtain higher efficiency photovoltaic devices at reduced cost of production so that solar electricity can be cost competitive. The majority of photovoltaic technologies are based on p-n junction, with efficiency potential being much lower than the thermodynamic limits of individual technologies and thereby providing substantial scope for further improvements in efficiency. The thesis explores photovoltaic devices using new physical processes that rely on thin layers and are capable of attaining the thermodynamic limit of photovoltaic technology. Silicon heterostructure is one of the candidate technologies in which thin films induce a …

Contributors
Ghosh, Kunal, Bowden, Stuart, Honsberg, Christiana, et al.
Created Date
2011

Silicon solar cells with heterojunction carrier collectors based on a-Si/c-Si heterojunction (SHJ) have a potential to overcome the limitations of the conventional diffused junction solar cells and become the next industry standard manufacturing technology of solar cells. A brand feature of SHJ technology is ultrapassivated surfaces with already demonstrated 750 mV open circuit voltages (Voc) and 24.7% efficiency on large area solar cell. Despite very good results achieved in research and development, large volume manufacturing of high efficiency SHJ cells remains a fundamental challenge. The main objectives of this work were to develop a SHJ solar cell fabrication flow using …

Contributors
Herasimenka, Stanislau Yur'Yevich, Honsberg, Christiana B, Bowden, Stuart G, et al.
Created Date
2013

This PhD thesis consists of three main themes. The first part focusses on modeling of Silver (Ag)-Chalcogenide glass based resistive memory devices known as the Programmable Metallization Cell (PMC). The proposed models are examined with the Technology Computer Aided Design (TCAD) simulations. In order to find a relationship between electrochemistry and carrier-trap statistics in chalcogenide glass films, an analytical mapping for electron trapping is derived. Then, a physical-based model is proposed in order to explain the dynamic behavior of the photodoping mechanism in lateral PMCs. At the end, in order to extract the time constant of ChG materials, a method …

Contributors
Saremi, Mehdi, Goodnick, Stephen M, Vasileska, Dragica, et al.
Created Date
2017

Thin-film modules of all technologies often suffer from performance degradation over time. Some of the performance changes are reversible and some are not, which makes deployment, testing, and energy-yield prediction more challenging. The most commonly alleged causes of instability in CdTe device, such as “migration of Cu,” have been investigated rigorously over the past fifteen years. As all defects, intrinsic or extrinsic, interact with the electrical potential and free carriers so that charged defects may drift in the electric field and changing ionization state with excess free carriers. Such complexity of interactions in CdTe makes understanding of temporal changes in …

Contributors
Guo, Da, Vasileska, Dragica, Sankin, Igor, et al.
Created Date
2017

This work is focused on modeling the reliability concerns in GaN HEMT technology. The two main reliability concerns in GaN HEMTs are electromechanical coupling and current collapse. A theoretical model was developed to model the piezoelectric polarization charge dependence on the applied gate voltage. As the sheet electron density in the channel increases, the influence of electromechanical coupling reduces as the electric field in the comprising layers reduces. A Monte Carlo device simulator that implements the theoretical model was developed to model the transport in GaN HEMTs. It is observed that with the coupled formulation, the drain current degradation in …

Contributors
Padmanabhan, Balaji, Vasileska, Dragica, Goodnick, Stephen M, et al.
Created Date
2013

Silicon photovoltaics is the dominant contribution to the global solar energy production. As increasing conversion efficiency has become one of the most important factors to lower the cost of photovoltaic systems, the idea of making a multijunction solar cell based on a silicon bottom cell has attracted broad interest. Here the potential of using dilute nitride GaNPAs alloys for a lattice-matched 3-terminal 2-junction Si-based tandem solar cell through multiscale modeling is investigated. To calculate the electronic band structure of dilute nitride alloys with relatively low computational cost, the sp^3 d^5 s^* s_N tight-binding model is chosen, as it has been …

Contributors
Zou, Yongjie, Goodnick, Stephen M., Honsberg, Christiana B., et al.
Created Date
2019

ABSTRACT An Ensemble Monte Carlo (EMC) computer code has been developed to simulate, semi-classically, spin-dependent electron transport in quasi two-dimensional (2D) III-V semiconductors. The code accounts for both three-dimensional (3D) and quasi-2D transport, utilizing either 3D or 2D scattering mechanisms, as appropriate. Phonon, alloy, interface roughness, and impurity scattering mechanisms are included, accounting for the Pauli Exclusion Principle via a rejection algorithm. The 2D carrier states are calculated via a self-consistent 1D Schrödinger-3D-Poisson solution in which the charge distribution of the 2D carriers in the quantization direction is taken as the spatial distribution of the squared envelope functions within the …

Contributors
Tierney, Brian David, Goodnick, Stephen, Ferry, David, et al.
Created Date
2011

Silicon photonic technology continues to dominate the solar industry driven by steady improvement in device and module efficiencies. Currently, the world record conversion efficiency (~26.6%) for single junction silicon solar cell technologies is held by silicon heterojunction (SHJ) solar cells based on hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si). These solar cells utilize the concept of carrier selective contacts to improve device efficiencies. A carrier selective contact is designed to optimize the collection of majority carriers while blocking the collection of minority carriers. In the case of SHJ cells, a thin intrinsic a-Si:H layer provides crucial passivation between doped …

Contributors
Muralidharan, Pradyumna, Goodnick, Stephen M, Vasileska, Dragica, et al.
Created Date
2019

This work demonstrates novel nBn photodetectors including mid-wave infrared (MWIR) nBn photodetectors based on InAs/InAsSb type-II superlattices (T2SLs) with charge as the output signal, and visible nBn photodetectors based on CdTe with current output. Furthermore, visible/MWIR two-color photodetectors (2CPDs) are fabricated through monolithic integration of the CdTe nBn photodetector and an InSb photodiode. The MWIR nBn photodetectors have a potential well for holes present in the barrier layer. At low voltages of < −0.2 V, which ensure low dark current <10-5 A/cm2 at 77 K, photogenerated holes are collected in this well with a storage lifetime of 40 s. This …

Contributors
He, Zhaoyu, Zhang, Yong-Hang, Vasileska, Dragica, et al.
Created Date
2016

This dissertation addresses challenges pertaining to multi-junction (MJ) solar cells from material development to device design and characterization. Firstly, among the various methods to improve the energy conversion efficiency of MJ solar cells using, a novel approach proposed recently is to use II-VI (MgZnCd)(SeTe) and III-V (AlGaIn)(AsSb) semiconductors lattice-matched on GaSb or InAs substrates for current-matched subcells with minimal defect densities. CdSe/CdTe superlattices are proposed as a potential candidate for a subcell in the MJ solar cell designs using this material system, and therefore the material properties of the superlattices are studied. The high structural qualities of the superlattices are …

Contributors
Li, Jing-Jing, Zhang, Yong-Hang, Tao, Meng, et al.
Created Date
2012

Polycrystalline CdS/CdTe solar cells continue to dominate the thin-film photovoltaics industry with an achieved record efficiency of over 22% demonstrated by First Solar, yet monocrystalline CdTe devices have received considerably less attention over the years. Monocrystalline CdTe double-heterostructure solar cells show great promise with respect to addressing the problem of low Voc with the passing of the 1 V benchmark. Rapid progress has been made in driving the efficiency in these devices ever closer to the record presently held by polycrystalline thin-films. This achievement is primarily due to the utilization of a remote p-n heterojunction in which the heavily doped …

Contributors
Becker, Jacob, Zhang, Yong-Hang, Bertoni, Mariana, et al.
Created Date
2017

This dissertation aims to study and understand the effect of nonlinear dynamics and quantum chaos in graphene, optomechanics, photonics and spintronics systems. First, in graphene quantum dot systems, conductance fluctuations are investigated from the respects of Fano resonances and quantum chaos. The conventional semi-classical theory of quantum chaotic scattering used in this field depends on an invariant classical phase-space structure. I show that for systems without an invariant classical phase-space structure, the quantum pointer states can still be used to explain the conductance fluctuations. Another finding is that the chaotic geometry is demonstrated to have similar effects as the disorders …

Contributors
Wang, Guanglei, Lai, Ying-Cheng, Vasileska, Dragica, et al.
Created Date
2017

Conductance fluctuations associated with quantum transport through quantumdot systems are currently understood to depend on the nature of the corresponding classical dynamics, i.e., integrable or chaotic. There are a couple of interesting phenomena about conductance fluctuation and quantum tunneling related to geometrical shapes of graphene systems. Firstly, in graphene quantum-dot systems, when a magnetic field is present, as the Fermi energy or the magnetic flux is varied, both regular oscillations and random fluctuations in the conductance can occur, with alternating transitions between the two. Secondly, a scheme based on geometrical rotation of rectangular devices to effectively modulate the conductance fluctuations …

Contributors
Ying, Lei, Lai, Ying-Cheng, Vasileska, Dragica, et al.
Created Date
2016

One of the challenges in future semiconductor device design is excessive rise of power dissipation and device temperatures. With the introduction of new geometrically confined device structures like SOI, FinFET, nanowires and continuous incorporation of new materials with poor thermal conductivities in the device active region, the device thermal problem is expected to become more challenging in coming years. This work examines the degradation in the ON-current due to self-heating effects in 10 nm channel length silicon nanowire transistors. As part of this dissertation, a 3D electrothermal device simulator is developed that self-consistently solves electron Boltzmann transport equation with 3D …

Contributors
Hossain, Arif, Vasileska, Dragica, Ahmed, Shaikh, et al.
Created Date
2011

In recent years, there has been increased interest in the Indium Gallium Nitride (InGaN) material system for photovoltaic (PV) applications. The InGaN alloy system has demonstrated high performance for high frequency power devices, as well as for optical light emitters. This material system is also promising for photovoltaic applications due to broad range of bandgaps of InxGa1-xN alloys from 0.65 eV (InN) to 3.42 eV (GaN), which covers most of the electromagnetic spectrum from ultraviolet to infrared wavelengths. InGaN’s high absorption coefficient, radiation resistance and thermal stability (operating with temperature > 450 ℃) makes it a suitable PV candidate for …

Contributors
Fang, Yi, Vasileska, Dragica, Goodnick, Stephen, et al.
Created Date
2017

Infrared photodetectors, used in applications for sensing and imaging, such as military target recognition, chemical/gas detection, and night vision enhancement, are predominantly comprised of an expensive II-VI material, HgCdTe. III-V type-II superlattices (SLs) have been studied as viable alternatives for HgCdTe due to the SL advantages over HgCdTe: greater control of the alloy composition, resulting in more uniform materials and cutoff wavelengths across the wafer; stronger bonds and structural stability; less expensive substrates, i.e., GaSb; mature III-V growth and processing technologies; lower band-to-band tunneling due to larger electron effective masses; and reduced Auger recombination enabling operation at higher temperatures and …

Contributors
Steenbergen, Elizabeth H., Zhang, Yong-Hang, Brown, Gail J., et al.
Created Date
2012

Sb-based type-II superlattices (T2SLs) are potential alternative to HgCdTe for infrared detection due to their low manufacturing cost, good uniformity, high structural stability, and suppressed Auger recombination. The emerging InAs/InAsSb T2SLs have minority carrier lifetimes 1-2 orders of magnitude longer than those of the well-studied InAs/InGaSb T2SLs, and therefore have the potential to achieve photodetectors with higher performance. This work develops a novel method to measure the minority carrier lifetimes in infrared materials, and reports a comprehensive characterization of minority carrier lifetime and transport in InAs/InAsSb T2SLs at temperatures below 77 K. A real-time baseline correction (RBC) method for minority …

Contributors
Lin, Zhiyuan, Zhang, Yong-Hang, Vasileska, Dragica, et al.
Created Date
2016

In this dissertation, I investigate the electronic properties of two important silicon(Si)-based heterojunctions 1) hydrogenated amorphous silicon/crystalline silicon (a-Si:H/c-Si) which has already been commercialized in Heterojunction with Intrinsic Thin-layer (HIT) cells and 2) gallium phosphide/silicon (GaP/Si) which has been suggested to be a good candidate for replacing a-Si:H/c-Si in HIT cells in order to boost the HIT cell’s efficiency. In the first part, the defect states of amorphous silicon (a-Si) and a-Si:H material are studied using density functional theory (DFT). I first employ simulated annealing using molecular dynamics (MD) to create stable configurations of a-Si:H, and then analyze the atomic …

Contributors
Vatan Meidanshahi, Reza, Goodnick, Stephen Marshall, Vasileska, Dragica, et al.
Created Date
2019

Scaling of the Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) towards shorter channel lengths, has lead to an increasing importance of quantum effects on the device performance. Until now, a semi-classical model based on Monte Carlo method for instance, has been sufficient to address these issues in silicon, and arrive at a reasonably good fit to experimental mobility data. But as the semiconductor world moves towards 10nm technology, many of the basic assumptions in this method, namely the very fundamental Fermi’s golden rule come into question. The derivation of the Fermi’s golden rule assumes that the scattering is infrequent (therefore the long …

Contributors
Jayaram Thulasingam, Gokula Kannan, Vasileska, Dragica, Ferry, David, et al.
Created Date
2017

New technologies enable the exploration of space, high-fidelity defense systems, lighting fast intercontinental communication systems as well as medical technologies that extend and improve patient lives. The basis for these technologies is high reliability electronics devised to meet stringent design goals and to operate consistently for many years deployed in the field. An on-going concern for engineers is the consequences of ionizing radiation exposure, specifically total dose effects. For many of the different applications, there is a likelihood of exposure to radiation, which can result in device degradation and potentially failure. While the total dose effects and the resulting degradation …

Contributors
Schlenvogt, Garrett James, Barnaby, Hugh, Goodnick, Stephen, et al.
Created Date
2014

GaAs single-junction solar cells have been studied extensively in recent years, and have reached over 28 % efficiency. Further improvement requires an optically thick but physically thin absorber to provide both large short-circuit current and high open-circuit voltage. By detailed simulation, it is concluded that ultra-thin GaAs cells with hundreds of nanometers thickness and reflective back scattering can potentially offer efficiencies greater than 30 %. The 300 nm GaAs solar cell with AlInP/Au reflective back scattering is carefully designed and demonstrates an efficiency of 19.1 %. The device performance is analyzed using the semi-analytical model with Phong distribution implemented to …

Contributors
Liu, Shi, Zhang, Yong-Hang, Johnson, Shane R, et al.
Created Date
2015

Wide bandgap (WBG) semiconductors GaN (3.4 eV), Ga2O3 (4.8 eV) and AlN (6.2 eV), have gained considerable interests for energy-efficient optoelectronic and electronic applications in solid-state lighting, photovoltaics, power conversion, and so on. They can offer unique device performance compared with traditional semiconductors such as Si. Efficient GaN based light-emitting diodes (LEDs) have increasingly displaced incandescent and fluorescent bulbs as the new major light sources for lighting and display. In addition, due to their large bandgap and high critical electrical field, WBG semiconductors are also ideal candidates for efficient power conversion. In this dissertation, two types of devices are demonstrated: …

Contributors
Fu, Houqiang, Zhao, Yuji, Vasileska, Dragica, et al.
Created Date
2019