A5103195493- Silicon and Solar Cell Technologies
- Thin-Film Transistor Technologies
- Semiconductor materials and interfaces
- Silicon Nanostructures and Photoluminescence
- Integrated Circuits and Semiconductor Failure Analysis
- Spectroscopy and Laser Applications
- solar cell performance optimization
- Nanowire Synthesis and Applications
- Semiconductor Lasers and Optical Devices
- Quantum Dots Synthesis And Properties
- Photonic and Optical Devices
- Semiconductor materials and devices
- Laser Design and Applications
- Atmospheric Ozone and Climate
- Photochemistry and Electron Transfer Studies
- Photonic Crystals and Applications
- Chalcogenide Semiconductor Thin Films
- Thermal Radiation and Cooling Technologies
- Advanced Surface Polishing Techniques
- Nuclear and radioactivity studies
- Laser Material Processing Techniques
- Optical Coatings and Gratings
- Spectroscopy Techniques in Biomedical and Chemical Research
- Nanofabrication and Lithography Techniques
- Organic Light-Emitting Diodes Research
Q-Cells (Germany)
2024
National Renewable Energy Laboratory
2010-2019
IBM (United States)
2011-2017
Fraunhofer Institute for Solar Energy Systems
2015-2016
University of Freiburg
2012
Harvard University
2007-2011
Harvard University Press
2006-2009
We demonstrate a compact, single-mode quantum cascade laser source continuously tunable between 8.7 and 9.4μm. The consists of an array distributed feedback lasers with closely spaced emission wavelengths fabricated monolithically on single chip driven by microelectronic controller. Our is suitable for variety chemical sensing applications. Here, we use it to perform absorption spectroscopy fluids.
The charge carrier transport mechanism of passivating contacts which feature an ultra-thin oxide layer is investigated by studying temperature-dependent current-voltage characteristics. 4-Terminal dark J-V measurements at low temperatures reveal non-linear characteristics with a homogeneously grown silicon oxide, result in exponential increase contact resistance towards lower temperature. attempt to describe the R(T) characteristic solely thermionic emission carriers across energy barrier...
We report here on the design, fabrication, and characterization of highly integrated parallel optical transceivers designed for Tb/s-class module-to-module data transfer through polymer waveguides into printed circuit boards (o-PCBs). The transceiver is based a through-silicon-via silicon carrier as platform integration 24-channel vertical cavity surface-emitting laser photodiode arrays with CMOS ICs. Si also includes vias (holes) access to conventional 850 nm optoelectronic devices....
Passivated contacts (poly-Si/SiOx/c-Si) doped by shallow ion implantation are an appealing technology for high efficiency silicon solar cells, especially interdigitated back contact (IBC) cells where a masked facilitates their fabrication. This paper presents study on tunnel oxide passivated formed low-energy into amorphous (a-Si) layers and examines the influence of species (P, B, or BF2), dose (5 × 1014 cm−2 to 1 1016 cm−2), subsequent high-temperature anneal (800 °C 900 °C) passivation...
Comparison of the measured absolute absorption cross section on a per Si atom basis plasma-synthesized nanocrystals (NCs) with bulk crystalline shows that while near band edge NC is weaker than bulk, yet above ∼2.2 eV absorbs up to 5 times more bulk. Using atomistic screened pseudopotential calculations we show this enhancement arises from interface-induced scattering enhances quasi-direct, zero-phonon transitions by mixing direct Γ-like wave function character into indirect X-like...
Wavelength beam combining was used to co-propagate beams from 28 elements in an array of distributed-feedback quantum cascade lasers (DFB-QCLs). The beam-quality product the array, defined as near-field spot size and far-field divergence for entire improved by a factor 21 using wavelength combining. To demonstrate applicability combined DFB-QCL arrays remote sensing, we obtained absorption spectrum isopropanol at distance 6 m laser array.
Abstract The surface of silicon nanocrystals embedded in an oxide matrix can contain numerous interface defects. These defects strongly affect the nanocrystals’ photoluminescence efficiency and optical absorption. Dangling‐bond are nearly eliminated by H 2 passivation, thus decreasing absorption below quantum‐confined bandgap enhancing PL order magnitude. However, there remain other seen photothermal deflection spectroscopy; these cause non‐radiative recombination that limits to <15%....
We report quantum chemical calculations using multireference perturbation theory (MRPT) with the density matrix renormalization group (DMRG) plus photothermal deflection spectroscopy measurements to investigate manifold of carotenoid excited states and establish their energies relative bright state (S2) as a function nuclear reorganization. conclude that primary photophysics carotenoids are determined by interplay only lowest-energy dark (S1) states. The lowest-lying state, far from being...
We describe the design, fabrication and results of passivated contacts to n-type silicon utilizing thin SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> indium tin oxide. High-temperature dioxide is grown on both surfaces an Si wafer a thickness <;50 Å, followed by deposition tin-doped oxide (ITO) patterned metal contacting layer. As deposited, thin-film stack has very high recombination parameter, J...
Luminescent solar concentrators (LSCs) harness light generated by luminophores embedded in a light-trapping waveguide to concentrate onto smaller cells. LSCs can absorb both direct and diffuse sunlight, thus operate as flat plate receivers at fixed tilt with conventional module form factor. However, current experience significant power loss through parasitic luminophore absorption incomplete trapping the optical waveguide. Here, we introduce tandem LSC device architecture that overcomes of...
We form gallium-doped poly-Si:Ga/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> passivated contacts on n-type Czochralski (n-Cz) wafers using ion implantation of Ga and Ga-containing spin-on dopants. After annealing passivation with Al O xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , the exhibit iVoc values >730 mV corresponding Joe <;5 fA/cm <sup xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . These are among...
Drop-coated high-refractive-index nanoparticles used as a back reflector for thin-film solar cells are non-absorbing Mie-scatterers that enhance light trapping. We present optical measurements and theory this approach. A 40% enhancement of the photocurrent efficiency 2.5 μm thick single-crystal Si cell on display glass is achieved by adding 270 nm rutile TiO2 nanoparticles.
We describe the design, fabrication and results of passivated contacts to n-type silicon utilizing thin SiO2 transparent conducting oxide layers. High temperature dioxide is grown on both surfaces an wafer a thickness <50 Å, followed by deposition tin-doped indium (ITO) patterned metal contacting layer. As deposited, thin-film stack has very high J0,contact, non-ohmic, contact resistance. However, after forming gas anneal, passivation quality resistivity improve significantly. The are...
Transparent conductive adhesives (TCAs) can enable conductivity between two substrates, which is useful for a wide range of electronic devices. Here, we have developed TCA composed polymer–particle blend with ethylene-vinyl acetate as the transparent adhesive and metal-coated flexible poly(methyl methacrylate) microspheres particles that provide adhesion regardless surface texture. This layer was designed to be nearly transparent, in only out-of-plane direction, practical strength hold...
We investigate how SiOx oxide interlayers prepared by different techniques (chemical, thermal) in combination with hydrogen released from an ALD Al2O3 source layer govern passivation 1) passivated contacts based on doped poly-Si layers and tunneling SiO2, 2) wafer surface Al2O3. Profiles of O H these structures engineered, buried were measured Time-of-Flight SIMS (TOF-SIMS) at nanometer resolution. Passivated perform best thermally oxidized SiOx, while chemical causes film blistering...
In this Letter, we report the tuning of emission wavelength a single mode distributed feedback quantum cascade laser by modifying effective refractive index using fluids. A fabrication procedure to encapsulate devices in polymers for microfluidic delivery is also presented. The integration microfluidics with semiconductor (optofluidics) promising new compact and portable lab-on-a-chip applications.
A multiwavelength array of distributed feedback (DFB) quantum cascade lasers (QCLs) that spans λ = 8.28 to 9.62 μm is wavelength beam combined (WBC) using both single-grating and dual-grating designs. WBC with a single grating results in pointing error 3-times the divergence for laser arises from nonlinear dispersion grating. By adding second compensate dispersion, reduced only 13% laser. transceiver based on dual-grating-WBC QCL was used measure transmittance polymer sheet placed between...
We report growth and characterization of heteroepitaxial silicon solar cells on sapphire to demonstrate the promise crystal (c-Si) film photovoltaics inexpensive substrates coated with chemically inert crystalline buffer layers such as Al2O3. Our work isolates addresses critical material light-trapping issues that must be solved develop c-Si cells. Microscopy reveals high dislocation densities other defects in layers, these limit unhydrogenated devices a 1.5 μm absorber layer below 1%...
We identify bottlenecks, and propose solutions, to implement a B-diffused front emitter backside pc-Si/SiO2 pasivated tunneling contact into high efficiency n-Cz Si cells in an industrially relevant way. apply O-precipitate dissolution treatment make wafers immune bulk lifetime process degradation, enabling robust, passivated B emitters with J0 <; 20fA/cm2. Adding ultralow recombination n+ back contacts enables pre-metallized iVoc=720 mV J0=8.6 fA/cm2. However, metallization significantly...
A bilayer coating 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> and TiO is used to simultaneously achieve excellent passivation low reflectivity on p-type silicon. This targeted for achieving high efficiency n-wafer Si solar cells, where both anti-reflection (AR) are needed at the front-side emitter. It could also be valuable AR rear-emitter interdigitated back contact p-wafer...
The rapid increase of bandwidth requirements between processors in high-end servers motivates the integration optical interconnects on first-level processor package [1]. In this perspective, additional density can be achieved by integrating transceivers directly into die. Optically enabled CPUs provide energy-efficient, low-latency over long distances (>10m) future data-centers. Integrated photonic interconnect technology will require sensitive and low-power receiver (RX) circuits that...
We describe the design, fabrication, and results of low-recombination, passivated contacts to n-type silicon utilizing thin SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> , plasma enhanced chemical vapor deposited doped polycrystalline-silicon (pc-Si) layers. A low-temperature dioxide layer is grown on both surfaces an CZ wafer a thickness <;20 Å. Next, P-doped amorphous (n/a-Si:H) top . The layers are annealed crystallize a-Si:H...