P.J. Resnick

Sandia National Laboratories, Albuquerque, New Mexico, United States

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Publications (45)29.99 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Microsystems-enabled photovoltaics (MEPV) has great potential to meet the increasing demands for light-weight, photovoltaic solutions with high power density and efficiency. This paper describes effective failure analysis techniques to localize and characterize nonfunctional or underperforming MEPV cells. The defect localization methods such as electroluminescence under forward and reverse bias, as well as optical beam induced current using wavelengths above and below the device band gap, are presented. The current results also show that the MEPV has good resilience against degradation caused by reverse bias stresses.
    IEEE Journal of Photovoltaics 01/2014; 4(1):470-476. DOI:10.1109/JPHOTOV.2013.2284864 · 3.00 Impact Factor
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    ABSTRACT: A new deuterium ion source is being developed to improve the performance of existing compact neutron generators. The ion source is a microfabricated array of metal tips with an integrated gate (i.e., grid) and produces deuterium ions by field ionizing (or field desorbing) a supply of deuterium gas. Deuterium field ion currents from arrays at source temperatures of 77 K and 293 K are studied. Ion currents from single etched-wire tips operating under the same conditions are used to help understand array results. I-F characteristics of the arrays were found to follow trends similar to those of the better understood single etched-wire tip results; however, the fields achieved by the arrays are limited by electrical breakdown of the structure. Neutron production by field ionization at 293 K was demonstrated for the first time from microfabricated array structures with integrated gates.
    Journal of Applied Physics 11/2013; 114(17):174906-174906-9. DOI:10.1063/1.4826111 · 2.19 Impact Factor
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    ABSTRACT: We report on a demonstration prototype module created to explore the viability of using microscale solar cells combined with microlens array concentrators to create a thin, flat-plate concentrator module with a relatively large acceptance angle for use with coarse two-axis tracking systems designed for flat-plate, one-sun modules. The demonstration module was comprised of an array of 216 cell/microlens units and was manufactured using standard tools common to the integrated circuit, microelectromechanical system (MEMS), and electronics assembly industries. The module demonstrated an acceptance angle of ±4°, an optical concentration level of 36X, and a focal depth of 13.3 mm. The acceptance angle and focal depth of the system successfully demonstrated adequate performance for integration into a system using a coarse two-axis tracker for flat-plate modules. To fully take advantage of this system approach, significant future work is required to reduce optical losses, increase cell and module efficiency, reduce the focal length to approximately 5 mm, and increase the concentration level to greater than 100X while maintaining an acceptance angle of at least ±2°.
    2013 IEEE 39th Photovoltaic Specialists Conference (PVSC); 06/2013
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    ABSTRACT: We present ultra-thin single crystal mini-modules built with specific power of 450 W/kg capable of voltages of >1000 V/cm2. These modules are also ultra-flexible with tight bending radii down to 1 mm. The module is composed of hundreds of back contact microcells with thicknesses of approximately 20 μm and diameters between 500-720 μm. The cells are interconnected to a flexible circuit through solder contacts. We studied the characteristics of several mini-modules through optical inspection, evaluation of quantum efficiency, measurement of current-voltage curves, and temperature dependence. Major efficiency losses are caused by missing cells or non-interconnected cells. Secondarily, damage incurred during separation of 500 μm cells from the substrate caused material detachment. The detachment induced higher recombination and low performance. Modules made with the larger cells (720 μm) performed better due to having no missing cells, no material detachment and optimized AR coatings. The conversion efficiency of the best mini module was 13.75% with a total Voc = 7.9 V.
    2013 IEEE 39th Photovoltaic Specialists Conference (PVSC); 06/2013
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    ABSTRACT: Microsystem technologies have the potential to significantly improve the performance, reduce the cost, and extend the capabilities of solar power systems. These benefits are possible due to a number of significant beneficial scaling effects within solar cells, modules, and systems that are manifested as the size of solar cells decrease to the sub-millimeter range. To exploit these benefits, we are using advanced fabrication techniques to create solar cells from a variety of compound semiconductors and silicon that have lateral dimensions of 250 - 1000 mu m and are 1 - 20 mu m thick. These fabrication techniques come out of relatively mature microsystem technologies such as integrated circuits(IC) and microelectromechanical systems (MEMS) which provide added supply chain and scale-up benefits compared to even incumbent PV technologies.
    ECS Transactions 03/2013; 50(6):351-359. DOI:10.1149/05006.0351ecst
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    ABSTRACT: Microsystems-enabled photovoltaic (MEPV) technology is a promising approach to lower the cost of solar energy to competitive levels. This paper describes current development efforts to leverage existing silicon integrated circuit (IC) failure analysis (FA) techniques to study MEPV devices. Various FA techniques such as light emission microscopy and laser-based fault localization were used to identify and characterize primary failure modes after fabrication and packaging. The FA results provide crucial information used in provide corrective actions and improve existing MEPV fabrication techniques.
    Reliability Physics Symposium (IRPS), 2013 IEEE International; 01/2013
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    ABSTRACT: Back-contacted, ultrathin (<10 mu m), and submillimeter-sized solar cells made with microsystem tools are a new type of cell that has not been optimized for performance. The literature reports efficiencies up to 15% using thicknesses of 14 mu m and cell sizes of 250 mu m. In this paper, we present the design, conditions, and fabrication parameters necessary to optimize these devices. The optimization was performed using commercial simulation tools from the microsystems arena. A systematic variation of the different parameters that influence the performance of the cell was accomplished. The researched parameters were resistance, Shockley-Read-Hall (SRH) lifetime, contact separation, implant characteristics (size, dosage, energy, and ratio between the species), contact size, substrate thickness, surface recombination, and light concentration. The performance of the cell was measured with efficiency, open-circuit voltage, and short-circuit current. Among all the parameters investigated, surface recombination and SRH lifetime proved to be the most important. Through completing the simulations, an optimized concept solar cell design was introduced for two scenarios: high and low quality materials/passivation. Simulated efficiencies up to 23.4% (1sun) and 26.7% (100suns) were attained for 20-mu m-thick devices. Copyright (c) 2012 John Wiley & Sons, Ltd.
    Progress in Photovoltaics Research and Applications 05/2012; 21(5). DOI:10.1002/pip.2214 · 9.70 Impact Factor
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    ABSTRACT: The use of an electrostatic field desorption (EFD) ion source would constitute a significant advance in the design and operation of neutron generators. The results would directly benefit the use of neutron generators for active interrogation in the search for special nuclear material and the replacement of radioisotopic sources, particularly in man-portable scenarios. The novel EFD approach uses high electrostatic fields to produce pure atomic deuterium ions from a conductive surface, rather than ions produced from deuterium plasma. This concept has the potential to surpass current state of the art sealed neutron tube designs in many key performance areas including lifetime, reliability, efficiency, and neutron yield. Over the past few years a thorough study of the ion production and neutron yield of fabricated devices has been conducted. Devices that are 1 mm2 consistently produce approximately 1000 n/cm2/s from the deuteron-deuteron reaction when operating in the dc mode. Electric fields of 20 V/nm are consistently achieved resulting in molecular deuterium ions from field ionization. Further increases in electric fields are necessary to reliably produce deuterons from field desorption. Both the modeling and experimental results to date are discussed.
    Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2012 IEEE; 01/2012
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    ABSTRACT: We present the experimental procedure to create lattice mismatched multijunction photovoltaic (PV) cells using 3D integration concepts. Lattice mismatched multijunction photovoltaic (PV) cells with decoupled electrical outputs could achieve higher efficiencies than current-matched monolithic devices. Growing lattice mismatched materials as a monolithic structure generates defects and decreases performance. We propose using methods from the integrated circuits and microsystems arena to produce the PV cell. The fabricated device consists of an ultrathin (6 μm) series connected InGaP/GaAs PV cell mechanically stacked on top of an electrically independent silicon cell. The InGaP/GaAs PV cell was processed to produce a small cell (750 μm) with back-contacts where all of the contacts sit at the same level. The dual junction and the silicon (c-Si) cell are electrically decoupled and the power from both cells is accessible through pads on the c-Si PV cell. Through this approach, we were able to fabricate a functional double junction PV cell mechanically attached to a c-Si PV cell with independent connections.
    Photovoltaic Specialists Conference (PVSC), 2012 38th IEEE; 01/2012
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    ABSTRACT: An ion source based on the principles of electrostatic field desorption is being developed to improve the performance of existing compact neutron generators. The ion source is an array of gated metal tips derived from field electron emitter array microfabrication technology. A comprehensive summary of development and experimental activities is presented. Many structural modifications to the arrays have been incorporated to achieve higher tip operating fields, while lowering fields at the gate electrode to prevent gate field electron emission which initiates electrical breakdown in the array. The latest focus of fabrication activities has been on rounding the gate electrode edge and surrounding the gate electrode with dielectric material. Array testing results have indicated a steady progression of increased array tip operating fields with each new design tested. The latest arrays have consistently achieved fields beyond those required for the onset of deuterium desorption (˜20 V/nm), and have demonstrated the desorption of deuterium at fields up to 36 V/nm. The number of ions desorbed from an array has been quantified, and field desorption of metal tip substrate material from array tips has been observed for the first time. Gas-phase field ionization studies with ˜10,000 tip arrays have achieved deuterium ion currents of ˜50 nA. Neutron production by field ionization has yielded ˜102 n/s from ˜1 mm2 of array area using the deuterium-deuterium fusion reaction at 90 kV.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 01/2012; 663(1):64-74. DOI:10.1016/j.nima.2011.09.034 · 1.32 Impact Factor
  • M. Ziaei-Moayyed · P. Resnick · B. Draper · M. Okandan
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    ABSTRACT: This paper reports the radial bulk-mode vibrations in a gate-all-around (GAA) silicon nanowire (SiNW) transistor at 25.3GHz, with a quality factor of ∼850 measured in air. The radial bulk-mode resonance is excited capacitively in the SiNW using the surrounding gate and gate dielectric as the transducer; the output is sensed piezoresistively by modulating the drain current in SiNW. The SiNWs are defined using standard lithography in a top-down front-end CMOS process, which allows for resonators with different frequencies to be fabricated on the same chip.
    Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) 01/2012; DOI:10.1109/MEMSYS.2012.6170423
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    ABSTRACT: We present an approach to create ultrathin (<;20 μm) and highly flexible crystalline silicon sheets on inexpensive substrates. We have demonstrated silicon sheets capable of bending at a radius of curvature as small as 2 mm without damaging the silicon structure. Using microsystem tools, we created a suspended submillimeter honeycomb-segmented silicon structure anchored to the wafer only by small tethers. This structure is created in a standard thickness wafer enabling compatibility with common processing tools. The procedure enables all the high-temperature steps necessary to create a solar cell to be completed while the cells are on the wafer. In the transfer process, the cells attach to an adhesive flexible substrate which, when pulled away from the wafer, breaks the tethers and releases the honeycomb structure. We have previously demonstrated that submillimeter and ultrathin silicon segments can be converted into highly efficient solar cells, achieving efficiencies up to 14.9% at a thickness of 14 μm. With this technology, achieving high efficiency (>;15%) and highly flexible photovoltaic (PV) modules should be possible.
    IEEE Journal of Photovoltaics 07/2011; 1(1):3-8. DOI:10.1109/JPHOTOV.2011.2162973 · 3.00 Impact Factor
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    ABSTRACT: We report up to 75 times enhancement in emission from lithographically produced photonic crystals with postprocessing close-packed colloidal quantum-dot incorporation. In our analysis, we use the emission from a close-packed free-standing film as a reference. After discounting the angular redistribution effect, our analysis shows that the observed enhancement is larger than the combined effects of Purcell enhancement and dielectric enhancement with the microscopic local field. The additional enhancement mechanisms, which are consistent with all our observations, are thought to be spectral diffusion mediated by phonons and local polarization fluctuations that allow off-resonant excitons to emit at the cavity wavelengths.
    Journal of the Optical Society of America B 05/2011; 28(6):1365-1373. DOI:10.1364/JOSAB.28.001365 · 1.81 Impact Factor
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    ABSTRACT: Crystalline silicon solar cells 10–15 times thinner than traditional commercial c-Si cells with 14.9% efficiency are presented with modeling, fabrication, and testing details. These cells are 14 μm thick, 250 μm wide, and have achieved 14.9% solar conversion efficiency under AM 1.5 spectrum. First, modeling results illustrate the importance of high-quality passivation to achieve high efficiency in thin silicon, back contacted solar cells. Then, the methodology used to fabricate these ultra thin devices by means of established microsystems processing technologies is presented. Finally, the optimization procedure to achieve high efficiency as well as the results of the experiments carried out with alumina and nitride layers as passivation coatings are discussed.Graphical Abstract
    Solar Energy Materials and Solar Cells 02/2011; 95(2):551-558. DOI:10.1016/j.solmat.2010.09.015 · 5.34 Impact Factor
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    ABSTRACT: Microsystem-Enabled Photovoltaic (MEPV) cells allow solar PV systems to take advantage of scaling benefits that occur as solar cells are reduced in size. We have developed MEPV cells that are 5 to 20 microns thick and down to 250 microns across. We have developed and demonstrated crystalline silicon (c-Si) cells with solar conversion efficiencies of 14.9%, and gallium arsenide (GaAs) cells with a conversion efficiency of 11.36%. In pursuing this work, we have identified over twenty scaling benefits that reduce PV system cost, improve performance, or allow new functionality. To create these cells, we have combined microfabrication techniques from various microsystem technologies. We have focused our development efforts on creating a process flow that uses standard equipment and standard wafer thicknesses, allows all high-temperature processing to be performed prior to release, and allows the remaining post-release wafer to be reprocessed and reused. The c-Si cell junctions are created using a backside point-contact PV cell process. The GaAs cells have an epitaxially grown junction. Despite the horizontal junction, these cells also are backside contacted. We provide recent developments and details for all steps of the process including junction creation, surface passivation, metallization, and release.
    Proceedings of SPIE - The International Society for Optical Engineering 02/2011; DOI:10.1117/12.876422 · 0.20 Impact Factor
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    ABSTRACT: Reducing the thickness of crystalline silicon wafers has evolved in the solar industry. As of 2010, most of the silicon solar cell companies were working with 6 inch wafers with thicknesses between 180 and 200 µm. In addition, a significant portion of the crystalline silicon material is lost during sawing. The effective material usage is equivalent to a wafer with a thickness of 310–475 µm depending on the thickness of the cut wire. Although there is a strong cost driver to use thinner wafers, handling wafers thinner than 180 µm is challenging while maintaining adequate yield. We present an approach to create ultrathin (15%), highly-flexible PV modules should be possible with this approach.
  • P. J. Resnick · E. Langlois
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    ABSTRACT: MEMS processing technologies have been used to create a wide variety of devices, including photonic crystals and microfluidic structures. These methodologies were adapted to fabricate an in situ vacuum sealed cold-cathode diode. Cathodes were formed from arrays of tungsten-clad silicon tips. Tungsten anodes, separated by a sacrificial film, were fabricated above each tip, within a vacuum microcavity. Initial test data are consistent with Fowler-Nordheim behavior, with an on/off current ratio of nearly 7 decades in forward bias.
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    ABSTRACT: We present a newly developed microsystem enabled, back-contacted, shade-free GaAs solar cell. Using microsystem tools, we created sturdy 3 μm thick devices with lateral dimensions of 250 μm, 500 μm, 1 mm, and 2 mm. The fabrication procedure and the results of characterization tests are discussed below. The highest efficiency cell had a lateral size of 500 μm and a conversion efficiency of 10%, open circuit voltage of 0.9 V and a current density of 14.9 mA/cm<sup>2</sup> under one-sun illumination.
    Photovoltaic Specialists Conference (PVSC), 2010 35th IEEE; 07/2010
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    ABSTRACT: Thin and small form factor cells have been researched lately by several research groups around the world due to possible lower assembly costs and reduced material consumption with higher efficiencies. Given the popularity of these devices, it is important to have detailed information about the behavior of these devices. Simulation of fabrication processes and device performance reveals some of the advantages and behavior of solar cells that are thin and small. Three main effects were studied: the effect of surface recombination on the optimum thickness, efficiency, and current density, the effect of contact distance on the efficiency for thin cells, and lastly the effect of surface recombination on the grams per Watt-peak. Results show that high efficiency can be obtained in thin devices if they are well-passivated and the distance between contacts is short. Furthermore, the ratio of grams per Watt-peak is greatly reduced as the device is thinned.
    Photovoltaic Specialists Conference (PVSC), 2010 35th IEEE; 07/2010
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    ABSTRACT: Field emission arrays that are used for ion desorption must be capable of operating at high applied voltages. The large electric fields can lead to dielectric breakdown or electron emission from the gate, both of which may result in catastrophic failure. Methods were developed to fabricate tip arrays with integrated gate electrodes, separated from the substrate with sufficient dielectric to sustain high voltages. To suppress gate electron emission, processes were developed to fabricate geometries that favor high fields at the tip while minimizing the field at the gate.
    Microelectronic Engineering 05/2010; 87(5):1263-1265. DOI:10.1016/j.mee.2009.11.036 · 1.34 Impact Factor