A5085734881- solar cell performance optimization
- Chalcogenide Semiconductor Thin Films
- Semiconductor Quantum Structures and Devices
- Metal and Thin Film Mechanics
- Silicon and Solar Cell Technologies
- Metallic Glasses and Amorphous Alloys
- Nanowire Synthesis and Applications
- Advanced ceramic materials synthesis
- Semiconductor materials and devices
- Force Microscopy Techniques and Applications
- Quantum Dots Synthesis And Properties
- Thin-Film Transistor Technologies
- Nanofabrication and Lithography Techniques
- Surface Roughness and Optical Measurements
- ZnO doping and properties
- High-pressure geophysics and materials
- Adhesion, Friction, and Surface Interactions
- GaN-based semiconductor devices and materials
- Diamond and Carbon-based Materials Research
- Nuclear materials and radiation effects
- Ferroelectric and Piezoelectric Materials
- Electron and X-Ray Spectroscopy Techniques
- Integrated Circuits and Semiconductor Failure Analysis
- Photovoltaic System Optimization Techniques
- Advanced Surface Polishing Techniques
Colorado School of Mines
2015-2024
National Renewable Energy Laboratory
2014-2024
Sonic Concepts (United States)
2023
Phoenix (United States)
2023
Arizona State University
2023
University of Maryland, College Park
2022
Argonne National Laboratory
2022
National Institute of Standards and Technology
2022
SLAC National Accelerator Laboratory
2022
Stanford Synchrotron Radiation Lightsource
2022
An instrument capable of performing nanoindentation at temperatures up to 500 °C in inert atmospheres, including partial vacuum and gas near atmospheric pressures, is described. Technical issues associated with the technique (such as drift noise) tip erosion radiative heating transducer) are identified addressed. Based on these considerations, preferred operation conditions for testing various materials. As a proof-of-concept demonstration, hardness elastic modulus three materials measured:...
We have performed spatially continuous nanodynamic mechanical analysis on four organic-rich shale samples with different thermal maturities to extract the elastic modulus of kerogen particles. Aliquots were rigorously prepared, and three scans acquired from each aliquot. Subcritical nitrogen adsorption pore characterization was determine abundance kerogen-hosted porosity. To fully characterize system oil window, toluene then chloroform extraction remove pore-filling hydrocarbons prior...
The importance of exfoliation techniques increases as the semiconductor industry progresses toward thinner devices a way to reduce material costs and improve performance. controlled spalling technique is recently developed substrate removal process that utilizes physics fracture create wafer cleavage parallel surface at precise depth. In this letter, we apply principles linear elastic mechanics predict conditions needed exfoliate (100) GaAs desired thickness. Spalling can be initiated in...
Although fatigue failure is well documented in metallic glasses, the mechanism responsible for damage accumulation during cyclic loading below yield point remains elusive. This letter describes a high-resolution nanomechanical study of an Fe-based bulk glass subjected to nominal elastic range. An increase load was observed with increasing number subyield cycles, providing clean documentation kinematic irreversibility very small volumes material that experience no shear bands either prior or loading.
A combined program of experiments and simulations is used to study the problem cyclic indentation loading on metallic glasses. The use a spherical nanoindenter tip shear band formation in three glasses (two based Pd one Fe), after subjecting glass cycles load nominal elastic range. In all glasses, such lead significant increases required subsequently trigger first band. This hardening occurs progressively over several cycles, but eventually saturates. effect requires sufficient amplitude not...
Abstract Radical reduction of III–V device costs requires a multifaceted approach attacking both growth and substrate costs. Implementing removal reuse provides an opportunity for cost reduction. Controlled spalling allows thin devices from the expensive substrate; however, fracture‐based process currently generates surfaces with significant morphological changes compared to polished wafers. 49 single junction are fabricated across spalled surface full 50 mm germanium wafers without...
Commercial lithium-ion battery cells were cycled to various depths of discharge at rates while the relative capacities periodically measured. After 1000 cycles, lithium cobalt oxide (LiCoO2) cathode material was extracted from most severely aged cell. Nanoindentation performed on individual LiCoO2 particles. Fractures in these particles exhibited anisotropic behavior, which confirmed by electron microscopy and diffraction examination indicating both intra- inter-granular fracture occurred...
Abstract We propose a method for in situ characterization of the photovoltaic module power at standard test conditions, using superposition dark current–voltage ( I–V ) curve measured elevated stress temperature, during potential‐induced degradation (PID) testing. PID chamber studies were performed on several crystalline silicon designs to determine extent which temperature dependency maximum is affected by modules. The results principle show mismatch between and 25 °C, dependent design,...
Lack of crystalline order in amorphous alloys, commonly called metallic glasses (MGs), tends to make them harder and more wear-resistant than their counterparts. However, finding inexpensive MGs is daunting; one with enhanced wear resistance a further challenge. Relying on machine learning (ML) predictions alone requires highly precise model; however, incorporating high-throughput (HiTp) experiments into the search rapidly leads higher performing materials even from moderately accurate...
Knowledge of accurate values elastic modulus (Al1-xScx)N is required for design piezoelectric resonators and related devices. Thin films across the entire composition space are deposited characterized. Accuracy measurements improved quantified by removing influence substrate effects direct comparison experimental results with density functional theory calculations. The 5%-30% Sc compositional range particular interest applications covered at higher resolution here than in previous work....
Abstract A 24%‐efficient single‐junction GaAs solar cell grown directly on a faceted, spalled (100) substrate after in situ planarization growth by hydride vapor phase epitaxy (HVPE) is achieved. Controlled spalling, promising low‐cost reuse technique, produces large facets (100)‐oriented substrates due to the orientation of fracture planes used for lift‐off. Planarization HVPE offers path toward direct use these without costly polishing steps. Here, rate anisotropy enabling arising from...
We demonstrate the growth of homojunction GaInP solar cells by dynamic hydride vapor phase epitaxy for first time. Simple unpassivated n-on-p structures grown in an inverted configuration with gold back reflectors were analyzed. Short wavelength performance varied strongly emitter thickness, since collection was limited lack surface passivation. Collection base increased decreasing doping density, range 1 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML"...
One possible pathway toward reducing the cost of III-V solar cells is to remove them from their growth substrate by spalling fracture, and then reuse for multiple cells. Here we consider on spalled GaAs(100) substrates, which typically have faceted surfaces after spalling. To facilitate high-quality cells, these should be smoothed prior cell growth. In this study, show that can during organometallic vapor-phase epitaxy growth, but choice epilayer material modification various...
A process for rapid fabrication of metallic MEMS (microelectromechanical systems) without lithographic processing is presented. Using dimensionally scalable contact printing, 3D electromechanical structures (see figure) are fabricated and functionally tested. Flexible, paper-thin device arrays produced by this method may enable such applications as pressure sensing skins people vehicles, phased array detectors acoustic imaging, novel adaptive-texture display applications.
As market-dominant Si solar cell technology approaches its practical efficiency limit of 27.1%, a key challenge for the photovoltaic industry is to search low-cost ~1.7 eV top that can enable cost-competitive tandems with solar-to-electricity conversion exceeding 30%. III-V semiconductors offer tunable bandgap and unparalleled efficiencies tandem devices. However, their high manufacturing cost has been biggest impediment market entry. Hydride vapor phase epitaxy (HVPE) recently reemerged as...