1. P. S. Friedman Integrated Sensors, LLC
New PPS Structures
P. S. Friedman
Integrated Sensors, LLC
September 27, 2012
GE Meeting at University of Michigan

2. New Device Requirements
Reduce discharge capacitive coupling to neighboring cells, thus reducing RC- time constant and improving cell response times. This should also improve device saturation limit at high incident luminosity.
Improve cell isolation by physically restricting UV-photons and metastables from exciting neighboring cells.
Improve device efficiency by increasing effective discharge region and improving cell geometric fill-factor.
Improve device operating window by improving cell uniformity primarily in terms of discharge gap, gas gap and electrode uniformity.
Embed each cell with a series quenching resistor & reduce signal reflections.
Develop low mass, ultra-thin devices for specific DOE applications.
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3. Basic Device Structures
Columnar-Discharge Modified-PDPs: Basic structure investigated to date. Open cell configuration, high capacitance, low fill-factor, line resistors only.
Microcavity-Discharge PPS: New structure being fabricated and the primary focus of our current research efforts. First article components are now being evaluated. Fully-integrated devices to be assembled in early Projected advantages include: better cell isolation, lower capacitance, significantly higher fill-factor that should yield higher efficiency, better cell uniformity, and an individual current-limiting quench resistor in each cell.
Grid-Support PPS: Family of future structures that should be able to operate as either columnar-discharge or surface-discharge PPS devices. Such devices to have a closed cell configuration for improved cell isolation and lower capacitance, a current-limiting quench resistor in each cell, and improved cell uniformity. This family of structures should lend itself to several specialized applications including: ultra-thin, low mass devices such as that required for active pixel ion beam monitors in low-energy particle physics, use of conversion layers, and Gd-based PPS devices for neutron detectors.
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4. Columnar-Discharge Modified-PDP Structure
Concept drawing of “open-cell” electrode structure of 2-electrode, double-substrate, columnar-discharge (CD) configuration.
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5. Modified-PDP Commercial Panel
Modified DC-PDP columnar-discharge PPS test panel with “refillable” gas valve. Each HV-cathode line (i.e. column electrode) has a current-limiting quench resistor.
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6. Microcavity-PPS Discharge Structure
Side View concept drawing of isolated PPS cells. Geiger-mode discharges are confined electrically and optically to the cavity. Isolation resistors are surface mount, to be replaced by thick-film resistors in a 2nd generation device.
3D Concept Drawing – The cathodes are the metalized inner surface of each cavity, connected on bottom side to the cell resistors and the HV bus-bars. The gas flow channels and the perimeter seal channel are shown. The top plate shows the small sense (anode) electrode segments centered in each microcavity.
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7. Microcavity-PPS Fabrication
(Right) – Photo of fabricated microcavity-PPS back plate with gas and seal channels, gas evacuation/fill hole, and conductive via to cell quench resistor on backside. Cavities will be metallized over metal the vias to complete the HV-cathode discharge structure.
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8. Microcavity-PPS Design & Fabrication
(Left) – Scale drawing of backside of 2.2” microcavity PPS back plate showing each cell series resistor connected to HV-cathode bus-bars. (Right) – Fabricated PPS cavity test plate with fill-factor of ~ 60%.
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9. Transparent Microcavity-PPS Cover Plate
~ 40X (magnification)
~ 40X (magnification)
Photographs of transparent cover plate including alignment slot & hole, and cavity via holes for each cavity sense electrode (anodes). Dark marks are feature shadows.
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10. Microcavity Fabrication Technologies
30µ cavities
Photos of microcavities fabricated by various techniques, with cavity pitches as small as 40 µm attained. Top Right cavity pitch is ~ 120 µm. Bottom Right photo is cavity grid manufactured by low cost PDP technology with cell pitch of ~ 150 µm for displays that sell for ~ $0.03 per cm2. PPS cavity fill-factors of ~ 80% should be achievable.
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11. Ultra-Thin Cover Plate PPS
Grid-Support Structure
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12. Back Up Slides
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13. Gd-based PPS Neutron Detector
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