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Over the past year we have
developed technique and instrumentation to measure the
surface resistivity of various foils with a view to their
use as interpolating medium in GEM/Micromega detectors.
The following is a chronological list of these reports
with comments as to their usefulness as resistive foil
or accuracy of technique.
A description of the Carleton/STC-made four-point probe
and the use of the Keithley model 2400 SourceMeter is
also included.
- High Resistivity Measured on Large Dimension
Resistive Foils from Minnesota Using the Parallel
Strip Method
20 June, 2003.
Film Type: Film from Astral Technologies of Minnesota.
Comments: Unsuitable film, very high, widely varying
resistivity ( 25 to 100 MOhm) by method of resistive
strips; poor repeatability by four-point probe method
(surface damage with probe points?).
- Recent Strip Resistivity Measurements
4 July, 2003.
Film types: a) Nominally 2.5 MOhm per square, Astral
Technologies of Minnesota. b) 1 micron thick Germanium
, BMV Technologies of Ottawa.
Comments: a) High resistivity, ~5.6 MOhm per square.
b) Very high resistivity (unmeasurable even with 50V
test voltage).
- Resistivity of Carbon-filled Kapton Measured
by Four-point Probe and Resistive Strip Measurements
12 August,
2003 (Corrected Version of 7 January, 2004)
Film Type: 1 mil thick carbon-loaded Kapton, thought
to be Dupont Kapton XC, type 100XC10E7 (may in fact
be 100XC10E6, judging by result).
Comments: Comparative study of methods of resistive
strips (corrected for contact resistance) and four-point
probes. Relatively good agreement. Probe method used
100nA Carleton made current source. Repeatability study,
probe repeatability about 4%.
- Measurement of Dupont Kapton XC Film Resistance
with Applied Voltage (Corrected Version of 9 January,
2004)
2 September,
2003; 9 January,2004.
Film Type: Kapton XC, type 100XC10E7 (may be in fact
100XC10E6).
Comments: Five strips tested, 12 squares long, from
1 to 3000 volts per strip (42mV/cm to 125V/cm). Plot
of variation of surface resistivity with voltage gradient
presented. Wider voltage gradient and more accurate
measurements made below in report #5.
- Measurement of Dupont XC Kapton Resistive
Film with Applied Voltage Gradient, Part Two
9 September,2003.
Film Type: Dupont Kapton XC (same strips used as above
test #4).
Comments: Voltage gradient ranged from 1mV/cm to 10,000mV/cm
(5 decades of voltage gradient); Shows resistance is
constant to 5V/cm after which resistance falls (may
be due to self heating effects). 5 decade semi-log
plot of resistance/cm vs voltage gradient presented.
- Measurement of Dupont XC Kapton Resistive
Film with Applied Voltage Gradient, Part Three
15 September,
2003.
Film Types: Two James Ochsner of Dupont-supplied Kapton
XC Films: type #1: 1 x 10E6 Ohms/sq. @1V/cm. 3 x 10E5
Ohms/sq. @3V/cm. type #2: 2.8 x 10E6 Ohms/sq. @1V/cm.
Comments: Two types of film personally supplied by
James Ochsner of Dupont, only the type #2 film in stock
at Dupont. Semilog plot of resistance/cm with applied
voltage gradient can be supplied.
- Comparison of Surface resistance of Carbon-loaded
Kapton Film by Method of Four-point Probes and Resistive
Strips
3 October,
2003.
Film Types: 1) TRIUMF supplied Dupont 100XC10E6 film.
2) Ochsner supplied Dupont 100XC3x10E5 film 3) Ochsner
supplied Dupont 100XC2.8x10E6 film.
Comments: The comparison of strip and four-point probe
readings is made and differences discussed.
- The Carleton made four-point probe Drawing (#SP000)
made by Vance is supplied. The readings made with this
probe are accurate, repeatable and settle down to their
final values quickly (shielded leads to the source/DVM).
Spring loaded probe pins are .040" diameter Everett-Charles
#P5160G-1R1S/ PR541-1 on 5mm centers.
- The acquisition of the Keithley 2400 SourceMeter
speeds measurements. Shielded leads go directly to
one instrument. Excitation current is accurately and
quickly set.
Ernie
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