A5032379315- Nanowire Synthesis and Applications
- Advanced Sensor and Energy Harvesting Materials
- Thin-Film Transistor Technologies
- Advancements in Semiconductor Devices and Circuit Design
- Nanomaterials and Printing Technologies
- Surface Modification and Superhydrophobicity
- Silicon Nanostructures and Photoluminescence
- Optical Coatings and Gratings
- Photonic Crystals and Applications
- Photonic and Optical Devices
- Advanced Antenna and Metasurface Technologies
- Semiconductor materials and devices
- Electromagnetic wave absorption materials
- solar cell performance optimization
- ZnO doping and properties
- Plasmonic and Surface Plasmon Research
- Silicon and Solar Cell Technologies
- Perovskite Materials and Applications
- Adhesion, Friction, and Surface Interactions
- Semiconductor Quantum Structures and Devices
- Quantum Dots Synthesis And Properties
- GaN-based semiconductor devices and materials
- Photovoltaic System Optimization Techniques
- Electrocatalysts for Energy Conversion
- Electrowetting and Microfluidic Technologies
University of Pittsburgh
2015-2024
Manado State University
2021
Stanford University
2006-2010
University of California, Berkeley
2009-2010
Lawrence Berkeley National Laboratory
2009-2010
Optical properties of highly ordered Ge nanopillar arrays are tuned through shape and geometry control to achieve the optimal absorption efficiency. Increasing materials filling ratio is shown increase reflectance while simultaneously decreasing transmittance, with absorbance showing a strong diameter dependency. To enhance broad band optical efficiency, novel dual-diameter structure presented, small tip for minimal large base maximal effective coefficient. The enabled single-crystalline...
Materials and device architecture innovations are essential for further enhancing the performance of solar cells while potentially enabling their large-scale integration as a viable source alternative energy. In this regard, tremendous research has been devoted in recent years with continuous progress field. article, we review advancements nanopillar-based photovoltaics discussing future challenges prospects. Nanopillar arrays provide unique advantages over thin films areas optical...
We demonstrate that vertical subwavelength diameter nanowires exhibit tunable and selective resonant absorption using numerical simulations optical waveguide theory. Incident light on only excites hybrid TM-dominant HE(1m) leaky modes due to symmetry matching requirements. The transverse resonances associated with these result in strong enhancements may be adjusted by changing the nanowire diameter. In particular, fundamental HE(11) resonance tuned across a wide range of wavelengths is...
This paper reports a systematic study of the mechanical and electronic properties strained small diameter (0.7--2.6 nm) silicon nanowires (Si NWs) using ab initio density functional theory calculations. The values Young's modulus, Poisson ratio, band gap, effective mass, work function, deformation potentials are calculated for $⟨110⟩$ $⟨111⟩$ Si NWs. We find that quantum confinement in NWs splits conduction valleys decreases transport mass compared to bulk case. Consequently, additional...
Silicon nanowire arrays have been shown to demonstrate light trapping properties and promising potential for next-generation photovoltaics. In this paper, we performed systematic detailed simulation studies on the optical of silicon nanocone as compared nanowires arrays. Nanocone were found significantly improved solar absorption efficiencies over Detailed simulations revealed that nanocones superior due reduced reflection from their smaller tip transmission larger base. The enhanced be...
We report a comprehensive simulation and experimental study on the optical electronic properties of uniform ordered copper nanomeshes (Cu NMs) to determine their performance for transparent conductors. Our includes simulations role propagating modes in transmission experiments that demonstrate scalable, facile microsphere-based method fabricate NMs rigid quartz flexible polyethylene terephthalate substrates. The fabrication allows precise control over NM morphology with near-perfect...
Silicon nanowires (NWs) have potential use in many electronic and photonic applications. In this study, we systematically investigated the modification of Si NW structure for different sized NWs surface coverage (H, Br, Cl, I) using ab initio density functional theory calculations. The chemistry is shown to strong effects, comparable that quantum confinement, on band NWs. Electronic analysis reveals primary cause gap change suppression states as determined by strength bonds. results...
We studied the influence of geometric parameters on optical absorption gallium arsenide (GaAs) nanocone and nanowire arrays via finite difference time domain simulations. optimized structural to maximize ultimate efficiency across a range lengths from 100 1000 nm. Nanocone were found have improved solar absorption, short-circuit current density, efficiencies over for wide lengths. Detailed simulations reveal that nanocones superior due reduced reflection their smaller tip transmission larger...
We report an experimental study on the fabrication and characterization of hierarchical graphene/metal grid structures for transparent conductors. The structure allows uniform local current conductivity due to graphene exhibits low sheet resistance because microscale silver serves as a conductive backbone. Our samples demonstrate 94% diffusive transmission with 0.6 Ω/sq direct optical ratio σdc/σop 8900. may be improved by over 3 orders magnitude little decrease in compared graphene....
Medical textiles have a need for repellency to body fluids such as blood, urine, or sweat that may contain infectious vectors contaminate surfaces and spread other individuals. Similarly, viral has yet be demonstrated long-term mechanical durability is major challenge. In this work, we demonstrate simple, durable, scalable coating on nonwoven polypropylene textile both superhemophobic antivirofouling. The treatment consists of polytetrafluoroethylene (PTFE) nanoparticles in solvent thermally...
We present a simulation and experimental study of silver meshes to determine their performance for transparent electromagnetic interference (EMI) shielding. Simulations were employed the effects mesh's width, pitch, thickness on EMI shielding efficiency (SE) in 8-18 GHz frequency range transparency visible spectrum. demonstrate scalable, facile fabrication method that involves embedding glass by etching trenches filling curing reactive particle-free ink these trenches. Our achieve 58.4 dB SE...
We report a study of the effect growth orientation and surface roughness on electron transport in small-diameter hydrogen passivated silicon nanowires (NWs). employ nonequilibrium Green's function technique within an $s{p}^{3}{d}^{5}{s}^{*}$ tight-binding approximation to show that band structure strongly affects current-voltage characteristics ideal NWs, leading current falloff at high drain bias for certain orientations. Surface suppresses small conductance current, leads nonmonotonic...
One of the challenges for nanoscale device fabrication III-V semiconductors is controllable postdeposition doping techniques to create ultrashallow junctions. Here, we demonstrate nanoscale, sulfur InAs planar substrates with high dopant areal dose and uniformity by using a self-limiting monolayer approach. From transmission electron microscopy secondary ion mass spectrometry, profile abruptness ∼3.5 nm/decade observed without significant defect density. The n+/p+ junctions fabricated this...
Conventional connectors utilize mechanical, magnetic, or electrostatic interactions to enable highly specific and reversible binding of the components (i.e., mates) for a wide range applications. As are miniaturized small scales, number shortcomings, including low strength, high engagement/disengagement energies, difficulties with engagement, fabrication challenges, lack reliability presented that limit their successful operation. Here, we report unisex, chemical based on hybrid,...
Abstract Boiling is a key heat transfer process for variety of power generation and thermal management technologies. We show that nanopillar arrays fabricated on substrate enhance both the critical flux (CHF) temperature at CHF thus, effectively increase limit boiling before crisis triggered. reveal enhancement in results from an intensified rewetting which increases with height nanopillars. develop predictive model based experimental measurements velocity to predict substrates. This...
Nanostructured superclear, superomniphobic glass fabricated by a statistical machine learning procedure.
Nitrogen-doped carbon nanotubes (NCNTs) have demonstrated great promise as an electrocatalyst alternative to platinum for oxygen reduction reaction (ORR). However, there is much disagreement regarding which N doping sites are most desirable the reaction. Here, we report experimental and computational study identify efficient active in NCNTs ORR alkaline media. In our experiments, synthesized of similar overall content (∼4.1%) matrix but varying percentages different types species. Our...
This work demonstrates a coal-derived functionalized nano-graphene oxide coating applied to fabrics that exhibits antiviral properties even after mechanical abrasion or bleach washing. Nano-graphene is chemically exfoliated from low cost coal and with octadecylamine render repellency properties. The polyethylene terephthalate (PET) fabric wet etching which roughens the microfiber surface for better adhesion liquid repellency. An additional polydimethylsiloxane (PDMS) layer on top of further...