Golden, CO, United States

Ampulse Corporation

www.ampulse.com
Golden, CO, United States
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Teplin C.W.,National Renewable Energy Laboratory | Paranthaman M.P.,Oak Ridge National Laboratory | Fanning T.R.,Ampulse Corporation | Alberi K.,National Renewable Energy Laboratory | And 15 more authors.
Energy and Environmental Science | Year: 2011

Crystal silicon (c-Si) film photovoltaics (PV) fabricated on inexpensive substrates could retain the desirable qualities of silicon wafer PV - including high efficiency and abundant environmentally-benign raw materials - at a fraction of the cost. We report two related advances toward film c-Si PV on inexpensive metal foils. First, we grow heteroepitaxial silicon solar cells on 2 kinds of single-crystal Al 2O 3 layers from silane gas, using the rapid and scalable hot-wire chemical vapor deposition technique. Second, we fabricate heteroepitaxial c-Si layers on large-grained, cube-textured NiW metal foils coated with Al 2O 3. In both experiments, the deposition temperature is held below 840 °C, compatible with low fabrication costs. The film c-Si solar cells are fabricated on both single-crystal sapphire wafer substrates and single-crystal γ-Al 2O 3-buffered SrTiO 3 wafer substrates. We achieve ∼400 mV of open-circuit voltage despite crystallographic defects caused by lattice mismatch between the silicon and underlying substrate. With improved epitaxy and defect passivation, it is likely that the voltages can be improved further. On the inexpensive NiW metal foils, we grow MgO and γ-Al 2O 3 buffer layers before depositing silicon. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) confirm that the silicon layers are epitaxial and retain the ∼50 μm grain size and biaxial orientation of the foil substrate. With the addition of light-trapping, >15% film c-Si PV on metal foils is achievable. © 2011 The Royal Society of Chemistry.


Grover S.,National Renewable Energy Laboratory | Teplin C.W.,National Renewable Energy Laboratory | Li J.V.,National Renewable Energy Laboratory | Bobela D.C.,Ampulse Corporation | And 7 more authors.
IEEE Journal of Photovoltaics | Year: 2013

We characterize heterojunction solar cells made from single-crystal silicon films grown heteroepitaxially using hot-wire chemical vapor deposition (HWCVD). Heteroepitaxy-induced dislocations limit the cell performance, providing a unique platform to study the device physics of thin crystal Si heterojunction solar cells. Hydrogen passivation of these dislocations enables an open-circuit voltage VOC close to 580 mV. However, dislocations are partially active, even after passivation. Using standard characterization methods, we compare the performance of heteroepitaxial absorbers with homoepitaxial absorbers that are free of dislocations. Heteroepitaxial cells have a smaller diffusion length and a larger ideality factor, indicating stronger recombination, which leads to inefficient current collection and a lower V OC than homoepitaxial cells. Modeling indicates that the recombination in the inversion layer of heterojunction cells made from defective absorbers is comparable with the overall recombination in the bulk. Temperature-dependent VOC measurements point to significant recombination at the interface that is attributable to the presence of dislocations. © 2011-2012 IEEE.


Wee S.H.,Oak Ridge National Laboratory | Cantoni C.,Oak Ridge National Laboratory | Fanning T.R.,Ampulse Corporation | Teplin C.W.,National Renewable Energy Laboratory | And 8 more authors.
Energy and Environmental Science | Year: 2012

Heteroepitaxial semiconductor films on low-cost, flexible metal foil templates are a potential route to inexpensive, high-efficiency solar cells. Here, we report epitaxial growth of Si films on low-cost, flexible, biaxially-textured Ni-W substrates. A robust buffer architecture comprised of multiple epitaxial oxide layers has been developed to grow high quality, heteroepitaxial Si films without any undesired reaction between the Si film and the metal substrate and with a single biaxial texture. XRD analysis including ω-scans, φ-scans, and pole figures confirms that the buffers and silicon are all epitaxial, with excellent cube-on-cube epitaxy. A photo-conversion efficiency of 1.1% is demonstrated from a proof-of-concept heteroepitaxial film Si solar cell. © 2012 The Royal Society of Chemistry.


Teplin C.W.,National Renewable Energy Laboratory | Lee B.G.,National Renewable Energy Laboratory | Fanning T.R.,Ampulse Corporation | Wang J.,Ampulse Corporation | And 6 more authors.
Energy and Environmental Science | Year: 2012

We report growth and characterization of heteroepitaxial silicon solar cells on sapphire to demonstrate the promise of heteroepitaxial crystal silicon (c-Si) film photovoltaics on inexpensive substrates coated with chemically inert crystalline buffer layers such as Al2O3. Our work isolates and addresses critical material and light-trapping issues that must be solved to develop film c-Si solar cells. Microscopy reveals high dislocation densities and other crystalline defects in the silicon layers, and these defects limit the unhydrogenated devices with a 1.5 μm absorber layer to below 1% sunlight-to-electricity conversion efficiency. By exposing an identical device to atomic H from a remote plasma, we demonstrate a 5.2% efficient device with dramatically improved quantum efficiency (QE) and open circuit voltage, as the minority carrier diffusion length increases from ∼1 μm to ∼4.5 μm. When we incorporate both hydrogen passivation and top surface pyramidal light trapping we further improve the QE and achieve 6.8% efficiency. This journal is © The Royal Society of Chemistry 2012.


Bolen M.L.,National Renewable Energy Laboratory | Grover S.,National Renewable Energy Laboratory | Teplin C.W.,National Renewable Energy Laboratory | Bobela D.,Ampulse Corporation | And 2 more authors.
Conference Record of the IEEE Photovoltaic Specialists Conference | Year: 2012

Post-deposition hydrogenation by remote plasma significantly improves performance of heteroepitaxial silicon (Si) solar cells. Heteroepitaxial deposition of thin crystal Si on sapphire for photovoltaics (PV) is an excellent model system for developing the PV technology platform of film c-Si on inexpensive Al2O3-coated (100) biaxially-textured metal foils. Without hydrogenation PV conversion efficiencies are less than 1% in our model system, due to carrier recombination at electrically-active dislocations and other growth defects. Hydrogenation dramatically improves performance, with low-temperature hydrogenation at 350oC being more effective than hydrogenation at 610°C. Spectral quantum efficiency, secondary ion mass spectrometry (SIMS), and vibrational Si-Hx Raman spectroscopy measurements elucidate the effects of hydrogenation on the materials and devices. Quantum efficiency increases at wavelengths >400 nm, indicating hydrogenation is mostly affecting the bulk of the cells. SIMS detects nearly 100 times more hydrogen atoms in our cells than available dangling bonds along all dislocations. Yet, Raman spectroscopy indicates that only low temperature hydrogenation creates Si-Hx bonds; trapped hydrogen does not stably passivate dangling-bond recombination sites at high temperatures. © 2012 IEEE.


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: | Award Amount: 149.94K | Year: 2010

This Small Business Technology Transfer (STTR) Phase I project aims to develop roll-to-roll processing of highly efficient, thin film photovoltaics on inexpensive polycrystalline substrates. The innovation lies in an architecture that yields near-single-crystalline thin films even on polycrystalline substrates. This innovation will be combined with the benefits of hot wire chemical vapor deposition (HWCVD) for Si film deposition. A key objective of this project is to demonstrate a high-rate HWCVD process for epitaxial Si layer on single-crystalline-like templates to fabricate high-efficiency solar cells on metal substrates. A strong emphasis will be placed on minimizing sources of defects and developing a comprehensive understanding of the impacts of these parameters on structural, electronic and photovoltaic properties of epitaxial thin film heterostructures.

The broader/commercial impact of this project will be the potential to provide a viable solution that enables high efficiency and low manufacturing cost without using scarce materials in Photovoltaics devices. In addition to commercial potential, a strong understanding of the mechanisms of epitaxial growth, grain boundaries, and defect generation and propagation is expected to be derived from this work.


Grant
Agency: National Science Foundation | Branch: | Program: STTR | Phase: Phase I | Award Amount: 149.94K | Year: 2010

This Small Business Technology Transfer (STTR) Phase I project aims to develop roll-to-roll processing of highly efficient, thin film photovoltaics on inexpensive polycrystalline substrates. The innovation lies in an architecture that yields near-single-crystalline thin films even on polycrystalline substrates. This innovation will be combined with the benefits of hot wire chemical vapor deposition (HWCVD) for Si film deposition. A key objective of this project is to demonstrate a high-rate HWCVD process for epitaxial Si layer on single-crystalline-like templates to fabricate high-efficiency solar cells on metal substrates. A strong emphasis will be placed on minimizing sources of defects and developing a comprehensive understanding of the impacts of these parameters on structural, electronic and photovoltaic properties of epitaxial thin film heterostructures. The broader/commercial impact of this project will be the potential to provide a viable solution that enables high efficiency and low manufacturing cost without using scarce materials in Photovoltaics devices. In addition to commercial potential, a strong understanding of the mechanisms of epitaxial growth, grain boundaries, and defect generation and propagation is expected to be derived from this work.


Trademark
Ampulse Corporation | Date: 2010-07-01

Electrical apparatus and instruments for the generation and transformation of electrical energy from photovoltaic and/or solar sources, namely, photovoltaic solar modules, solar wafers made of silicon and solar panels.


Trademark
Ampulse Corporation | Date: 2010-07-01

Electrical apparatus and instruments for the generation and transformation of electrical energy from photovoltaic and/or solar sources, namely, photovoltaic solar modules, solar wafers made of silicon and solar panels.

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