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Full-Text Articles in Engineering Science and Materials

Self-Aligned Double Pattern, No1, Yinong Cao May 2016

Self-Aligned Double Pattern, No1, Yinong Cao

Protocols and Reports

No abstract provided.


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 ...


Phase Boundary Propagation In Mass Spring Chains And Long Molecules, Qingze Zhao Jan 2016

Phase Boundary Propagation In Mass Spring Chains And Long Molecules, Qingze Zhao

Publicly Accessible Penn Dissertations

Martensitic phase transitions in crystalline solids have been studied and utilized for many technological applications, including biomedical devices. These transitions typically proceed by the nucleation and propagation of interfaces, or phase boundaries. Over the last few decades, a continuum theory of phase transitions has emerged under the framework of thermoelasticity to study the propagation of these phase boundaries. It is now well-established that classical mechanical and thermodynamic principles are not sufficient to describe their motion within a continuum theory, and a kinetic relation must be supplied to complete the constitutive description. A few theoretical techniques that have been used to ...


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 ...


Continuum And Computational Modeling Of Flexoelectricity, Sheng Mao Jan 2016

Continuum And Computational Modeling Of Flexoelectricity, Sheng Mao

Publicly Accessible Penn Dissertations

Flexoelectricity refers to the linear coupling of strain gradient and electric polarization. Early studies of this subject mostly look at liquid crystals and biomembranes. Recently, the advent of nanotechnology revealed its importance also in solid structures, such as flexible electronics, thin films, energy harvesters, etc. The energy storage function of a flexoelectric solid depends not only on polarization and strain, but also strain-gradient. This is our basis to formulate a consistent model of flexoelectric solids under small deformation. We derive a higher-order Navier equation for linear isotropic flexoelectric materials which resembles that of Mindlin in gradient elasticity. Closed-form solutions can ...


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 ...