A5000367042- Thin-Film Transistor Technologies
- Silicon and Solar Cell Technologies
- Semiconductor materials and interfaces
- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- solar cell performance optimization
- Perovskite Materials and Applications
- Photovoltaic System Optimization Techniques
- Silicon Nanostructures and Photoluminescence
- Semiconductor Quantum Structures and Devices
- Nanowire Synthesis and Applications
- Superconducting Materials and Applications
- Photochemistry and Electron Transfer Studies
- Photonic Crystals and Applications
- Magnetic confinement fusion research
- Photonic and Optical Devices
- Integrated Circuits and Semiconductor Failure Analysis
- ICT Impact and Policies
- Metabolism and Genetic Disorders
- Amino Acid Enzymes and Metabolism
- Electrostatic Discharge in Electronics
- Optical Coatings and Gratings
- Semiconductor materials and devices
- Advanced Materials and Mechanics
- Electrical Fault Detection and Protection
Arizona State University
2017-2023
University of Maryland, College Park
2001
Siemens (Germany)
1991
Tuning band gaps with three halides Tandem solar cells can boost cell efficiency by using two active layers to absorb the spectrum more completely, provided that are current-matched. Inorganic-organic perovskites tuned appropriate wide gap (∼1.7 electron volts) as top contained iodine and bromine or chlorine have short carrier diffusion lengths undergo photo-induced phase segregation. Xu et al. now report a method for incorporating chloride allows fabrication of stable triple-halide 1.67...
III–V/Si epitaxial tandems with a 1.7-eV GaAsP top cell promise stable power conversion efficiencies above the fundamental limit of Si single-junction cells. However, have suffered from limited minority carrier diffusion length in cell, leading to reduced short-circuit current densities (JSC) and efficiencies. While conventional wisdom dictates that dislocation density must be boost efficiency, here, we show heterointerface design growth sequence also play critical roles reducing...
In silicon heterojunction solar cells made with high-lifetime wafers, resistive losses in the contacts dominate total electrical power loss. Moreover, it is widely believed that hole contact stack-a-Si:H(i)/a-Si:H(p)/ITO/Ag-is responsible for more of this loss than electron stack. article, we vary a-Si:H(i) layer thickness, a-Si:H(p) thickness and doping, indium tin oxide (ITO) determine effect each variation on resistivity addition, make complete same variations correlate their series to...
Luminescent solar concentrators are currently limited in their potential concentration factor and conversion efficiency by the inherent escape cone losses present conventional planar dielectric waveguides. We demonstrate that photonic crystal slab waveguides tailored for luminescent concentrator applications can exhibit >90% light trapping efficiency. This is achieved use of quantum dot luminophores embedded within waveguide absorb at photon energies corresponding to leaky modes couple...
Due to the low temperature processing constraint in silicon heterojunction (SHJ) solar cells, no defect engineering improve wafer quality is typically incorporated during cell fabrication. This means that high‐quality n‐type Cz wafers are required produce high‐efficiency cells. Herein, recent demonstrations of incorporating approaches, such as gettering and hydrogenation, into SHJ process flow for both p‐type surveyed. Defect on before fabrication can significantly low‐lifetime wafers,...
Silicon heterojunction (SHJ) solar cell device structures use carrier-selective contacts that enable efficient collection of majority carriers while impeding the minority carriers. However, these can also be a source resistive losses degrade performance cell. In this article, we evaluate hole contact- hydrogenated amorphous silicon (a-Si:H)(i)/a-Si:H(p)/indium tin oxide (ITO)/Ag-by simulating transport in SHJ transfer length method structures. We study contact resistivity behavior by varying...
Silicon heterojunction solar cell fabrication incorporates a significant amount of hydrogen into the silicon wafer bulk, and injected is comparable to that introduced by nitride films during high-temperature firing step. In this work, origins processing have been identified. We demonstrate plasma treatment routinely included improve surface passivation considerably increases concentration in wafers. also show hydrogenated amorphous i/p+ stack more effective than i/n+ for bulk incorporation,...
Complete regeneration of boron-oxygen-related (BO) defects has been demonstrated on n-type upgraded metallurgical-grade (UMG) Czochralski-grown silicon heterojunction solar cells. Under accelerated conditions (93 suns, 220 °C), VOC fully recovered in 30–100 s and remained stable during a subsequent stability test. milder (3 180 the kinetics were slowed down by more than an order magnitude, but recovery was still complete stable. The stabilized UMG cells is 709 mV–722 mV, similar to...
Abstract We characterize a-Si:H(i)/a-Si:H(n)/Al and a-Si:H(i)/a-Si:H(p)/Al contacts implemented on the rear side of silicon heterojunction solar cells. Electrical test structures full-area cells employing these demonstrate promising performance. For example, with a 40 nm thick a-Si:H(p) layer that were annealed at 180 °C had contact resistivities 48 mΩ · cm 2 implied open-circuit voltage losses after metallization only 9 mV. Similarly, 150 voltages 717 mV 9.4 . thinner doped a-Si:H layers...
Herein, low‐cost p‐type upgraded metallurgical‐grade (UMG) multicrystalline silicon wafers are processed from the edge of cast using a multi‐stage defect‐engineering approach, incorporating gettering and hydrogenation to improve wafer quality. Significant reductions in concentration interstitial iron improvements bulk lifetime 15 130 µs observed. Subsequently, all surface layers removed heterojunction solar cells fabricated. The exhibit an efficiency 18.7%, open‐circuit voltages over 690 mV...
The results of two different series life tests carried out on vacuum switches with a self-produced axial magnetic field (in view their use in nuclear fusion facilities) are presented. goal was to obtain large number (on the order 2000) interruptions unidirectional current over 50 kA, recovery voltage up 35 kV. A first showed that test procedure an accelerated not adequate; it also apparent contact plate, designed for Hz applications, had weak points when subjected extended thermal contacts....
Silicon heterojunction solar cells are a promising device architecture due to their high efficiencies, yet these tend suffer from series resistances. Until recently, little has been done understand the main factors contributing resistance. Here we begin systematic analysis determine important interactions between different layers in hole-collecting contact consisting of stack a-Si:H(i)/aSi:H(p)/ITO/Ag. We attempt address how performs when intrinsic amorphous silicon (a-Si:H(i)) layer...
Silicon heterojunction (SHJ) solar cells have recently seen a boost in popularity sparked from their high efficiency capabilities. In order to reduce cost, some studies demonstrated the potential of p-type wafers as an alternative base material. However, very few investigated existence and influence light-induced degradation (LID) on SHJ cells, problem which has been significant hurdle for conventional devices. this work, we first identify presence severity LID A modified UNSW advanced...
We investigate the effect of Si random pyramid texturing on 1.7eV/1.1eV GaAs <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.77</sub> P xmlns:xlink="http://www.w3.org/1999/xlink">0.23</sub> /Si 2-terminal tandem solar cells (hereafter GaAsP/Si). Due to light trapping effect, rear surface increases short-circuit current density bottom cell by 2.76 mA/cm <sup xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> relative an untextured cell. For...
The first step to understand the origin of losses in any photovoltaic solar cell is determine fundamental thermodynamic efficiency and voltage limits such a device. In this contribution, we detail techniques calculate limit case cadmium selenium telluride (CdSeTe) cells, how approaches based on bandgap alone-i.e., Shockley-Queisser approach with step-function absorptance-can overestimate open-circuit Voc,ideal. This particularly true for arsenic-doped samples, which tend exhibit...
We report spectrally selective visible wavelength reflectors using hydrogenated amorphous silicon carbide (a-SiC:H) as a high index contrast material. Beyond 610nm and through the near infrared spectrum, a-SiC:H exhibits very low loss an averaged of refraction n = 3.1. Here we design, fabricate, characterize such hexagonal array nanopillars wavelength-selective mirrors with stop-band approximately 40 nm full-width at half maximum. The fabricated grating reflectivity R >94% resonance 642nm...
This paper investigates the impact of tabula rasa (TR) and phosphorus diffusion gettering (PDG), both in isolation combination, for improving electronic quality n-type Czochralski grown Upgraded Metallurgical-Grade (UMG) silicon wafers. We have found that bulk lifetimes UMG wafers were affected by oxygen precipitate nuclei mobile metallic impurities. Thus, we achieved best after subjecting to a TR step prior PDG step. Further, report heterojunction solar cells results based on subjected The...
Silicon heterojunction solar cells have historically suffered from high series resistivities. Yet, until recently, little had been done to understand the main factors behind this behavior. In work, we present a systematic analysis in order quantify and characterize contribution each layer of a-Si:H(i)/aSi:H(n)/ITO/Ag electron contacts. We attempt address how stack performs when its constituent layers are altered, using transfer length method. Specifically, demonstrate thickness a-Si:H doping...
A thin layer of Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> at the back CdSe xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> T xmlns:xlink="http://www.w3.org/1999/xlink">e1-x</sub> /CdTe devices is shown to passivate interface and drastically improve surface recombination lifetimes photoluminescent response. Despite this, such do not show an improvement in open-circuit...