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Full-Text Articles in Engineering Science and Materials

Influence Of Flow Rate, Nozzle Speed, Pitch And The Number Of Passes On The Thickness Of S1805 Photoresist In Suss Microtec As8 Spray Coater, Rohan Sanghvi, Gyuseok Kim Oct 2019

Influence Of Flow Rate, Nozzle Speed, Pitch And The Number Of Passes On The Thickness Of S1805 Photoresist In Suss Microtec As8 Spray Coater, Rohan Sanghvi, Gyuseok Kim

Tool Data

S1805 positive photoresist has been deposited on single crystalline Si wafers using a Suss MicroTec Alta Spray. The influence of flow rate, nozzle speed, pitch and number of passes on the thickness of the photoresist was studied. Results show that the thickness of S1805 is linearly proportional to the flow rate and number of passes, and inversely proportional to the nozzle speed and pitch.


Correction Of Pattern Size Deviations In The Fabrication Of Photomasks Made With A Laser Direct-Writer, Ningzhi Xie, George Patrick Watson Oct 2019

Correction Of Pattern Size Deviations In The Fabrication Of Photomasks Made With A Laser Direct-Writer, Ningzhi Xie, George Patrick Watson

Protocols and Reports

When using Heidelberg DWL66+ laser writer to fabricate the photomask, the pattern feature dimensions may have deviations. These deviations can be caused by the lithography process and the undercut in the metal etch process. The same deviation value of 0.8µm was found to appear in all the patterns independent of the pattern original size and local pattern density. To overcome this universal deviation, a universal bias is suggested to be applied to the original patterns during the data preparation for the lithography process. In order to ensure this pre-exposure bias method can work, both the laser direct-write exposure conditions ...


Grain-Boundary Kinetics And Nonequilibrium Grain-Boundary Structure, Jian Han Jan 2018

Grain-Boundary Kinetics And Nonequilibrium Grain-Boundary Structure, Jian Han

Publicly Accessible Penn Dissertations

Microstructure of polycrystalline materials can be described as grain boundary (GB) networks; hence, GBs play major role in a wide-range of polycrystal properties. Control over GB kinetics provides effective means to tailor polycrystal properties through material processing. Understanding and prediction of GB kinetic behavior are always central problems in materials science. In this thesis, these are realized based on a mechanistic model. The mechanistic model describes a GB as intrinsic GB structure decorated by extrinsic defects. GB kinetics is described by the transition among all the stable/metastable intrinsic GB structures and the kinetics of GB defects. A major type ...


Controlled Folding In Precisely Functionalized Polyethylenes: Designing Nanoscale Lamellar Structures For Ion Transport, Edward Boynton Trigg Jan 2018

Controlled Folding In Precisely Functionalized Polyethylenes: Designing Nanoscale Lamellar Structures For Ion Transport, Edward Boynton Trigg

Publicly Accessible Penn Dissertations

There is great societal need for improved energy storage technology, in applications ranging from electric vehicles to grid storage to emergency power systems. New polymeric membranes with enhanced ion conductivities are needed in batteries and fuel cells to improve these technologies. Despite decades of research, these membrane materials are still not adequate for commercial use. The primary metric that requires improvement is ion or proton conductivity of the membrane under desirable operating conditions.

Modifying linear polyethylene by the addition of precisely periodic functional groups leads to a rich array of intriguing morphologies and properties. Depending on the functional group chemistry ...


Atomic Force Microscopy-Based Investigation Of Plastic Deformation Mechanisms In Disordered Nanoparticle Packings, Joel Allen Lefever Jan 2018

Atomic Force Microscopy-Based Investigation Of Plastic Deformation Mechanisms In Disordered Nanoparticle Packings, Joel Allen Lefever

Publicly Accessible Penn Dissertations

Understanding the plastic deformation mechanisms of disordered materials is a longstanding and complex problem in condensed matter physics and materials science. In particular, the elementary plastic rearrangement in a disordered material is believed to be the shear transformation zone, a localized cooperative motion of a handful of constituents. Although observed in mesoscale systems, the shear transformation zone has never been identified in an experiment at the nanoscale. In the present work, atomic force microscopy is used to probe the mechanical response of thin films of disordered nanoparticle packings that have been deposited by spin-coating and layer-by-layer deposition. Results demonstrate that ...


The Role Of Sliding Contact In Nanoscale Tribochemistry, Zachary Banks Milne Jan 2018

The Role Of Sliding Contact In Nanoscale Tribochemistry, Zachary Banks Milne

Publicly Accessible Penn Dissertations

In this dissertation, the results of experimental and theoretical studies exploring friction

and adhesion at the nanoscale are presented. Using a customized in situ transmission

electron microscopy nanoindentation methodology, it is observed that cohesion of silicon and

adhesion of silicon and diamond are strongly modied by the sliding speed and the normal

stress applied during sliding. This indicates that shear stress modulates the reactivity of the

surfaces. This is the rst time that tunable adhesion of hard contacts has been demonstrated

in situ.

If sliding experiments are performed in ultra-high vacuum and the interfacial shear stress

is low enough to ...


Mechanics Of Colloidal Assemblies, Daniel James Strickland Jan 2017

Mechanics Of Colloidal Assemblies, Daniel James Strickland

Publicly Accessible Penn Dissertations

Amorphous solids -- solids that lack long-range order of their constituent particles -- are common in both nature and industry. Window glass, dense polymers, and food grains are three examples of amorphous solids familiar to us. In many amorphous solids, shear banding -- plastic deformation in which strain is accumulated in a thin band of the material -- is common. Consequently, many amorphous solids are brittle, a trait which has limited the technological adoption of otherwise promising materials such as metallic glasses. Therefore, a fundamental understanding of shear banding -- i.e., the progression from particle level plastic events to a macroscopic shear band, identification ...


Quantum Electronic Interference In Nano Amorphous Silicon And Other Thin Film Resistance Memory, Yang Lu Jan 2017

Quantum Electronic Interference In Nano Amorphous Silicon And Other Thin Film Resistance Memory, Yang Lu

Publicly Accessible Penn Dissertations

This thesis describes conductivity in amorphous semiconductors and insulators—some doped with metals, in which elastic electrons can random walk across a transport length of ~10 nm. At low temperatures, back diffusion of coherent electrons causes constructive quantum interference that leads to reduced diffusivity/conductivity. Rich physics also arises in this so-called weak-localization (WL) regime from electron-phase mutilation by spin-orbit interaction (weak-antilocalization or WAL) and magnetic modulation, and from Friedel-oscillation-enhanced backscattering and Zeeman splitting (electron-electron-interaction or EEI). Conductivity is analyzed by a new tool to eliminate contact resistance without using the four-point-probe method.

The Aharonov-Bohm oscillation in magnetoresistance affords the ...


Flexible, Photopatterned, Colloidal Cdse Semiconductor Nanocrystal Integrated Circuits, Franklin Scott Stinner Jan 2017

Flexible, Photopatterned, Colloidal Cdse Semiconductor Nanocrystal Integrated Circuits, Franklin Scott Stinner

Publicly Accessible Penn Dissertations

As semiconductor manufacturing pushes towards smaller and faster transistors, a parallel goal exists to create transistors which are not nearly as small. These transistors are not intended to match the performance of traditional crystalline semiconductors; they are designed to be significantly lower in cost and manufactured using methods that can make them physically flexible for applications where form is more important than speed. One of the developing technologies for this application is semiconductor nanocrystals.

We first explore methods to develop CdSe nanocrystal semiconducting “inks” into large-scale, high-speed integrated circuits. We demonstrate photopatterned transistors with mobilities of 10 cm2/Vs on ...


Cation Kinetics And Electric Field Effect In Zirconia, Yanhao Dong Jan 2017

Cation Kinetics And Electric Field Effect In Zirconia, Yanhao Dong

Publicly Accessible Penn Dissertations

Cation diffusion controls mass transport and microstructural evolution in zirconia above 1200 oC. In past research, its experimentally measured activation energy of 5 eV cannot be reproduced by computer simulation, which gives >10 eV and a cation vacancy mechanism implicating enhanced diffusion in oxidizing atmosphere, contradicting experimental evidence. This thesis was undertaken to answer these questions and to explore new ground in cation kinetics.

To help search for low-energy configurations in zirconia alloys, we employed crystal chemistry to boost sampling efficiency, by >1,000 times, and obtained plausible “ground states” to launch ab-initio calculations for cation defects and migration. The ...


Understanding Dewetting Transitions On Nanotextured Surfaces: Implications For Designing Surfaces With Improved Wettability, Suruchi Fialoke Jan 2017

Understanding Dewetting Transitions On Nanotextured Surfaces: Implications For Designing Surfaces With Improved Wettability, Suruchi Fialoke

Publicly Accessible Penn Dissertations

Despite the early promise of superhydrophobic surfaces, their widespread technological adoption has been dawdled by the ease with which water can penetrate the surface texture, resulting in a breakdown of superhydrophobicity. Furthermore, this breakdown is believed to be irreversible, because large adhesion barriers impede the dewetting of the surface texture and the concomitant recovery of superhydrophobicity. Using molecular dynamics simulations in conjunction with advanced sampling techniques, in this thesis, we challenge this conventional argument. We show that while large barriers do typically impede the recovery of superhydrophobicity, it can nevertheless be recovered spontaneously on nanotextured surfaces, wherein collective water density ...


Interfacial Assembly In Aqueous Two Phase Systems, Sarah Danielle Hann Jan 2017

Interfacial Assembly In Aqueous Two Phase Systems, Sarah Danielle Hann

Publicly Accessible Penn Dissertations

Stabilizing bio-friendly and cyto-mimetic fluid structures has important implications for drug and gene delivery, micro bio-reactors, single cell and microniche studies, and as protocells. The majority of stabilization techniques have been developed for oil-in-water and water-in-oil emulsions, which have limitations in their application to biological systems due to the presence of the oil phase. The structures built in this thesis are therefore made within water-in-water dispersions. These all water dispersions are from aqueous mixtures of two polymers that demix to form two phases, termed aqueous two phase systems (ATPSs). ATPSs are comprised of two water-rich phases and are therefore excellent ...


Mechanics Of Fluctuating Elastic Plates And Fiber Networks, Xiaojun Liang Jan 2017

Mechanics Of Fluctuating Elastic Plates And Fiber Networks, Xiaojun Liang

Publicly Accessible Penn Dissertations

Lipid membranes and fiber networks in biological systems perform important mechanical functions at the cellular and tissue levels. In this thesis I delve into two detailed problems -- thermal fluctuation of membranes and non-linear compression response of fiber networks. Typically, membrane fluctuations are analysed by decomposing into normal modes or by molecular simulations. In the first part of my thesis, I propose a new semi-analytic method to calculate the partition function of a membrane. The membrane is viewed as a fluctuating von Karman plate and discretized into triangular elements. Its energy is expressed as a function of nodal displacements, and then ...


Ii-Vi Semiconductor Nano-Structures For On-Chip Integrated Photonics, Jacob Stern Berger Jan 2016

Ii-Vi Semiconductor Nano-Structures For On-Chip Integrated Photonics, Jacob Stern Berger

Publicly Accessible Penn Dissertations

Nanowires (NWs) and nanobelts (NBs) have been widely studied and fabricated into on-chip photodetectors, biosensors, LEDs/lasers, solar cells and computational components. Their highly tunable physical, electronic and optical properties have generated interest in this field over the past two decades. While there is tremendous potential for nano-structured devices, the wide spread application of NWs/NBs has been hindered by the difficulty in integrating multiple NW or NB structures together into more complex devices. This problem requires a completely novel approach to what has been previously attempted in order to effectively couple on-chip light sources, waveguides and detectors. Multiple factors ...


Effects Of Nanoscale Aggregation On Mechanical Properties And Local Dynamics Of Precise Acid- And Ion-Containing Polymers, Luri Robert Middleton Jan 2016

Effects Of Nanoscale Aggregation On Mechanical Properties And Local Dynamics Of Precise Acid- And Ion-Containing Polymers, Luri Robert Middleton

Publicly Accessible Penn Dissertations

Acid- and ion-containing polymers have interchain interactions that alter polymer behavior at the nano, micro, and bulk length scales. Strong secondary-bonds act as thermo-reversible physical crosslinks between chains which drive self-assembly. Tuning theses interactions can modify bulk polymer properties including stiffness, toughness, melt viscosity, resilience, clarity, abrasion resistance and puncture resistance. Furthermore, understanding and improving the relevant factors that control transport properties would have vast implications on developing solid polymer electrolytes (SPEs) for technologically important applications including water desalination, ion exchange membranes and microelectronics. This thesis explores the structure – processing – morphology - property relationships of acid and ionic functionalized polymers.

Improvements ...


First Principles Studies Of Magnetic Oxides, Spin-Driven Ferroelectricity, And The Effect Of Polarization In The Chemistry Of Functional Heterointerfaces, Diomedes Saldana-Greco Jan 2016

First Principles Studies Of Magnetic Oxides, Spin-Driven Ferroelectricity, And The Effect Of Polarization In The Chemistry Of Functional Heterointerfaces, Diomedes Saldana-Greco

Publicly Accessible Penn Dissertations

Achieving accurate description and understanding of the chemical and physical properties of complex materials enables the further development of their technological applications. Employing density functional theory (DFT) with rotationally invariant Hubbard corrections, we present an extensive study of binary manganese oxides modeling their noncollinear spin patterns and computing their electronic structures in agreement with experimental results. Leveraging on our success in predicting accurately magnetic properties, we explore the noncollinear cycloidal magnetic order in CaMn$_{7}$O$_{12}$, which breaks inversion symmetry generating one of the largest spin-driven ferroelectric polarizations measured to date. Based on a generalized spin-current model ...


Liquid Crystal Anchoring Control And Its Applications In Responsive Materials, Yu Xia Jan 2016

Liquid Crystal Anchoring Control And Its Applications In Responsive Materials, Yu Xia

Publicly Accessible Penn Dissertations

Liquid crystals (LCs), owing to their anisotropy in molecular ordering, are of interests not only in the display industry, but also in the soft matter community, e.g., to direct colloidal assembly and phase separation of surfactants, and to actuate two-dimensional (2D) sheets into three-dimension (3D). The functionality and performance of LC materials extensively rely on the molecular ordering and alignment of LCs, which are dictated by LC anchoring at various boundaries. Therefore, this thesis focuses on the study of LC anchoring from both small molecule LCs and liquid crystal monomers (LCMs), which in turn guides my design of surface ...


Microwave Impedance Microscopy Of Nanostructured Carbon, Timothy Scott Jones Jan 2016

Microwave Impedance Microscopy Of Nanostructured Carbon, Timothy Scott Jones

Publicly Accessible Penn Dissertations

Microwave impedance microscopy (MIM) is a scanning probe technique that measures local changes in tip-sample admittance. The imaginary part of the reported change is calibrated with finite element simulations and physical measurements of a standard capacitive sample, and thereafter the output ∆Y is given a reference value in siemens. Simulations also provide a means of extracting sample conductivity and permittivity from admittance, a procedure verified by comparing the estimated permittivity of polytetrafluoroethlyene (PTFE) to the accepted value. Finally, the well-known effective medium approximation of Bruggeman is considered as a means of estimating the volume fractions of the constituents in inhomogeneous ...


Elucidating The Mechanical Response Of Metallic Glasses Prepared In Different Structural States At Sub-Micron Length Scales, Daniel J. Magagnosc Jan 2016

Elucidating The Mechanical Response Of Metallic Glasses Prepared In Different Structural States At Sub-Micron Length Scales, Daniel J. Magagnosc

Publicly Accessible Penn Dissertations

Metallic glasses (MGs) exhibit both high yield stresses and elastic strain limits owing to their metallic bonding character and lack of long-range order. Yet the structural state (i.e. local atomic packing), and the corresponding elastic and plastic mechanical response, of MGs is nuanced and dependent on processing history. Moreover, the interplay between small length scales and glass processing routes have produced seemingly conflicting results. Here, the influence of processing on MG mechanical behavior at sub-micron length scales is explored, revealing extreme sensitivity to ion irradiation, enhanced control over the mechanical response, and an underpinning of yield strength in thermodynamic ...


Engineering Phonon, Photon, Electron And Plasmon Interactions In Silicon - Metal Nanocavitiies For Silicon Photonics And Thermoplasmonics, Daksh Agarwal Jan 2016

Engineering Phonon, Photon, Electron And Plasmon Interactions In Silicon - Metal Nanocavitiies For Silicon Photonics And Thermoplasmonics, Daksh Agarwal

Publicly Accessible Penn Dissertations

ENGINEERING PHONON, PHOTON, ELECTRON AND PLASMON INTERACTIONS IN SILICON - METAL NANOCAVITIIES FOR SILICON PHOTONICS AND THERMOPLASMONICS

Daksh Agarwal

Ritesh Agarwal, PhD

Silicon photonics offers a cost effective solution to achieve ultrafast data processing speeds. But due to its indirect bandgap structure, making lasers from silicon is extremely difficult. Thus research has focused on nonlinear Raman processes in silicon as a method to achieve optical gain. Silicon nanowires provide an interesting platform for enhancing these nonlinearities because of their small size, geometry and relevant length scales. In the current work Raman measurements done on silicon nanowires reveal that up to twelvefold ...


Development And Characterization Of Next-Generation Contact Materials For Nanoelectromechanical Switches, Frank Streller Jan 2016

Development And Characterization Of Next-Generation Contact Materials For Nanoelectromechanical Switches, Frank Streller

Publicly Accessible Penn Dissertations

Nanoelectromechanical (NEM) switches were identified by the semiconductor industry as a low-power "beyond CMOS" technology. However, the reliability of the contact interface currently limits the commercialization of NEM switches, as the electrical contact has to be able to physically open and close up to a quadrillion (10^15) times without failing due to adhesion (by sticking shut) or contamination (reducing switch conductivity). These failure mechanisms are not well understood, and materials that exhibit the needed performance have not been demonstrated. Thus, commercially viable NEM switches demand the development of novel contact materials along with efficient methods to evaluate the performance ...


Multiscale Simulations Of Dynamics Of Ferroelectric Domains, Shi Liu Jan 2015

Multiscale Simulations Of Dynamics Of Ferroelectric Domains, Shi Liu

Publicly Accessible Penn Dissertations

Ferroelectric materials exhibiting switchable polarization have been used as critical components in electronics, memory, actuators and acoustics, and electro-optics. The applications of ferroelectric materials heavily rely on the interactions between the polarization and external perturbations, such as electric field, stress, and temperature. It is therefore crucial to understand the dynamics of ferroelectric response at finite temperature. Despite the tremendous advance of computational power and the success of first-principles methods, large-scale simulations of dynamics in oxides at finite temperature can still only be performed using classical atomistic potential. We first develop a model potential based on principles of bond-valence and bond-valence ...


Improving The Signal-To-Noise Of Nanopore Sensors, Matthew Puster Jan 2015

Improving The Signal-To-Noise Of Nanopore Sensors, Matthew Puster

Publicly Accessible Penn Dissertations

Over the last five years, solid state nanopore technology advanced to rival biological pores as a platform for next generation DNA sequencing. Fabrication improvements led to a reduction in nanopore diameter and membrane thickness, offering high precision sensing. Custom electronics were developed concomitant with low capacitance membranes for low-noise, high-bandwidth measurements. These advances improved our ability to detect small differences between translocating molecules and to measure short molecules translocating at high speeds.

This work focuses specifically on the challenge of maximizing the signal magnitude generated by the solid state nanopore. One way that this can be achieved is by thinning ...


Surface Reconstructions Of Perovskite-Type Oxides: Their Exotic Structures And Modified Chemistry, John Mark Pinat Martirez Jan 2015

Surface Reconstructions Of Perovskite-Type Oxides: Their Exotic Structures And Modified Chemistry, John Mark Pinat Martirez

Publicly Accessible Penn Dissertations

The ability to manipulate the atomic and electronic structures and stoichiometry of surfaces is of utmost importance in optimizing heterogeneous catalysts. A critical requirement in this endeavor is a deep thermodynamic and kinetic understanding of surface reconstruction behavior, under various thermal and chemical constraints. We explore the reconstruction behaviors (structure and chemistry) of Ti-based perovskite type oxides: BaTiO3, PbTiO3 and SrTiO3. The former two exhibit ferroelectricity. We find that these oxides undergo surface reconstruction transformations that generally result in enrichment of their catalytically active component: Ti. These reconstructions show rich bonding and structural motifs that affect the ...


Engineering Novel Nanostructures Via Chemical And Morphological Transformations, Rahul Agarwal Jan 2015

Engineering Novel Nanostructures Via Chemical And Morphological Transformations, Rahul Agarwal

Publicly Accessible Penn Dissertations

Materials at the nanoscale have revolutionized the world around us by enabling the discovery of novel size dependent properties and experimental verification of untested theoretical concepts. However, most nanomaterials today are phases of matter that are well known and have been studied extensively at the bulk scale. For example, II-VI semiconductors, which are widely studied today at the nanoscale, were employed in photovoltaic applications at the microscale for nearly half a century. The question that arises is whether material processing at the nanoscale can allow us to go beyond the limitations of conventional synthesis techniques? We believe that the next ...


Dynamics In Polymer Nanocomposites Containing Fixed And Mobile Nanoparticles, Chia-Chun Lin Jan 2015

Dynamics In Polymer Nanocomposites Containing Fixed And Mobile Nanoparticles, Chia-Chun Lin

Publicly Accessible Penn Dissertations

This dissertation describes experimental studies on the dynamics of polymer nanocomposites (PNC), namely, center-of-mass (COM) polymer diffusion in PNCs, and COM nanoparticle (NP) diffusion in polymer melts. Elastic recoil detection (ERD) is used for polymer diffusion studies and Rutherford backscattering (RBS) is used for NP diffusion studies. Diffusion of the tracer polymer, deuterated poly(methyl methacrylate) (dPMMA) is slowed down in a PMMA matrix filled with hydroxyl-capped spherical silica nanoparticles. A confinement parameter, ID/2Rg, where ID is interparticle distance and 2Rg is probe size is defined to account for the NP crowding effect. For highly crowded region where ID ...


Crystal-Amorphous Transformation Via Defect-Templating In Phase-Change Materials, Pavan Nukala Jan 2015

Crystal-Amorphous Transformation Via Defect-Templating In Phase-Change Materials, Pavan Nukala

Publicly Accessible Penn Dissertations

Phase-change materials (PCM) such as GeTe and Ge-Sb-Te alloys are potential candidates for non-volatile memory applications, because they can reversibly and rapidly transform between a crystalline phase and an amorphous phase with medium-range order. Traditionally, crystal-amorphous transformation in these materials has been carried out via melt-quench pathway, where the crystalline phase is heated beyond its melting point by the rising edge of an electric pulse, and the melt phase is quenched by the falling edge into a glassy phase. Formation of an intermediate melt phase in this transformation pathway requires usage of large switching current densities, resulting in energy wastage ...


Optical And Structural Studies Of Shape-Controlled Semiconductor Nanocrystals And Their Self-Assembled Solids, Benjamin Tavenner Diroll Jan 2015

Optical And Structural Studies Of Shape-Controlled Semiconductor Nanocrystals And Their Self-Assembled Solids, Benjamin Tavenner Diroll

Publicly Accessible Penn Dissertations

Colloidal nanocrystals are prominent candidates to displace current electronic active layers in solid-state device technologies and offer a body of physics which diverges from those of bulk materials and discreet molecules. Realizing the potential of colloidal nanocrystals may transform the costs and performance of common technologies, but understanding of the relationship between particle size, shape, uniformity, and composition and outputs like physical properties or device performance is often incomplete. This work uses the controlled synthesis of anisotropic colloidal nanocrystals to implement characterization techniques including X-ray diffraction and simulation, which allows an ensemble-level description of particle structure, as well as polarized ...


Form And Function: X-Ray Scattering And Spectroscopy Of Transition Metal-Based Nanoparticles, Vicky V T Doan-Nguyen Jan 2015

Form And Function: X-Ray Scattering And Spectroscopy Of Transition Metal-Based Nanoparticles, Vicky V T Doan-Nguyen

Publicly Accessible Penn Dissertations

In recent decades, nanoparticles have been found to possess unique, tunable properties with an enormous variety of applications. The atomic and nanoscale structures govern these functional properties, and structural deviations from the bulk, in part, are responsible for the vast technological uses of nanoparticles. This dissertation tackles the understanding of structure in a number of metal, metal phosphide, and metal oxide nanoparticle systems. Additionally, the syntheses of monodispersed nanoparticle systems allow for correlating their structure with functional properties. Real space analysis using pair distribution functions of monometallic (Ni, Pd) nanoparticles of less than 5 nm in diameter revealed a deviation ...


The Optoelectronic Properties Of Surface-Modified Semiconductor Nanocrystal Solids, Earl D. Goodwin Jan 2015

The Optoelectronic Properties Of Surface-Modified Semiconductor Nanocrystal Solids, Earl D. Goodwin

Publicly Accessible Penn Dissertations

Colloidal semiconductor nanocrystals have emerged as fascinating new materials and gained interest in the last 30 years because of their size, shape, and compositionally tunable electronic and optical properties as well as their potential to serve as artificial atoms. Challenges and opportunities have arisen when assembling nanocrystals into nanocrystal solids for electronic and optoelectronic applications, largely because of the significant influence of nanocrystal surface chemistry on the electronic, optical, and structural properties of nanocrystal solids. In order to assemble nanocrystal solids for high performance devices, we must understand and be able to control the effects of nanocrystal surface organic capping ...