Transcript GE_12.09.25_New-PPS-Structures_PSFx

New PPS Structures
P. S. Friedman
Integrated Sensors, LLC
September 27, 2012
GE Meeting at University of Michigan
New Device Requirements
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Reduce discharge capacitive coupling to neighboring cells, thus reducing RCtime 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.
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Embed each cell with a series quenching resistor & reduce signal reflections.
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Develop low mass, ultra-thin devices for specific DOE applications.
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Basic Device Structures
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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 2013. 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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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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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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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 thickfilm 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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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 HVcathode discharge structure.
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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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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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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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Ultra-Thin Cover Plate PPS
Grid-Support Structure
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Back Up Slides
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Gd-based PPS Neutron Detector
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