silicon carbide temperature sensor for harsh environments
TRANSCRIPT
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Silicon CarbideTemperature Sensor
for Harsh Environments
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Chris Rice Jason Wallace
Michael Jackson Jovan Bjelobrk
ADVISOR
Dr. Stephen Saddow“a hot project…a cool advisor”
Team Members
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Team Responsibilities
Jovan Bjelobrk
Jason Wallace
Michael Jackson
Chris Rice Sensor Fabrication
Sensor Testing
Sensor Fabrication
Sensor Testing
Software Interface
Device Controller
PIC Coding
Documentation
Device Controller
PIC Coding
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Overview
No reliable way to detect temperature changes in extreme environments using typical semiconductor material (Si)Space travel involves extreme temperaturesSiC has the ability to operate in and withstand extreme temperatures (>500 °C)
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Key Specifications
Increased Sensing Range 25 ° C to 500 ° C
Tolerance Temperature reading accuracy
of 0.5 °C at 25 °C
Cost Cost of working unit will be
less than $300
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Timeline
February March April MayHardware Sensor Circuit Board
Software PIC Programming User Interface
Performance TestingTroubleshootingFinished Product
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System Components
Temp. SensorController
CircuitSoftwareInterface
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PCB LAYOUT
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User Interface
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Design Equations
R = (L/A)
= 1/(qnn)
Ni = sqrt(Nc*Nv)*exp(-Eg/2kT)
n = (2.5*107)*T-2
A = W*t
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Resistance vs. Temperature
Test Spec of 25 to 500 degrees C
0 50 100 150 200 250 300 350 400 450 5000
1
2
3
4
5
6x 10
4
Temperature [C]
Res
ista
nce
[Ohm
s]L (m) =100
50
20
10
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Measured Resistance V. Temperature SiC
Resistance vs. Temperature
0
1
2
3
4
5
6
7
8
9
0 50 100 150
Temp [deg. C]
R (
Ko
hm
s)
10 5000
20 5000
50 5000
100 5000
20 1000
50 1000
100 1000
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SiC Sample
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MicropipesToday, the density of micropipe defects in standard SiC commercial wafers, which are being used as substrates for SiC device fabrication, exceeds 100 cm-2. These micropipes, originated from SiC substrates, penetrate in device structures during epitaxial growth and cause the device failure
"Silicon Carbide Epitaxial Wafers",http://www.tdii.com/sic-g.htm,Copyright 1997, 1998 by TDI, Inc
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Sensor Cross-Section
p+
n- n+ n+
I
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Resistance Model
R(n-)
R(p+)
R(n-): -- donor carriers fully ionized -- electron mobility controls R(n-)
R(p+): -- acceptor carriers are NOT fully ionized -- hole mobility is dominated by the hole ionization
= 1/(qnn)
= 1/(qpp)
R = (L/A)
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Fractional Ionization
Pd = 1E18 [cm-3]p = 10%(Pd) = 1E17 [cm-3]
p >> n
R(p+) << R(n-)
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Calculations
Re-worked Simulated Results,These are being generated!!!
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Cost Analysis~ $2000 per substrate (2 inch diameter wafer)
~ $600 for whole-wafer EPI Growth
~ $400 for Fabrication Run
Producing 24 cells per wafer, and assuming
overall yield of process of 72%, produces 120
usable devices at approximately $25 each
Control board components: $26.61
Total cost for working unit: $51.61
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Silicon CarbideTemperature Sensor
for Harsh Environments