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MOSFET Characteristics at Cryogenic Temperatures
Juan AvalosGraduate Mentor: Jingyi Tang
Faculty Advisor: Dr. Tolbert
University of Tennessee KnoxvilleREU CURENTJuly 14, 2016
Objective: Determine the semiconductor devices with the least energy losses to use in the DC-AC inverter for Boeing & NASA aircraft.
Devices: Microsemi, Infineon, IXYS
Characteristics:
On-state resistance
Body Diode
Switching Losses
Breakdown Voltage
2
On-State Resistance (RDS-ON)& Body Diode Schematic
• Same schematic, different settings
• RDS-ON gate input=10V
• Body diode gate input=0V
• Polarity changes opposite current paths
4
• Curve Tracer plots are used to calculate the on-state resistance.
• Use rated current and corresponding voltage
0.00E+00
2.00E+01
4.00E+01
6.00E+01
8.00E+01
1.00E+02
1.20E+02
0.00E+00 5.00E+00 1.00E+01 1.50E+01 2.00E+01
Dra
in C
urr
ent
(A)
Drain Source Voltage (V)
Curve Tracer Results
25 C
0 C
-30 C
-60 C
-90 C
-120 C
-150 C
-180 C
On-State Resistance Results (Infineon)
• Calculated on-state resistance using previous plot at different temperatures.
• RDS-ON= VDS/IRATED
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
-2.00E+02-1.50E+02-1.00E+02-5.00E+01 0.00E+00 5.00E+01
On
-Sta
te R
esi
sta
nce
(Ω
)
Temperature (C)
Temperature Effect
On-State Resistance Cont.
Body Diode
• Device in cut off region
• Polarity of input is reversed w/ respect to on-state resistance
• Reverse drain current shorts the source and drain
• High current path created through body diode
Results of Body Diode (Infineon)
0
10
20
30
40
50
60
70
80
90
100
0 0.5 1 1.5 2 2.5
Id(A
)
Vsd(V)
Switching Losses Schematic
Load Inductor
Upper Diode
Lower Switch
– +
DC Link Capacitor
Gate Driver
DC source
Signal Generator
Signal Isolator/
Logic
AUX Power Supply
Scope
Power Supply
Cryo. Chamber
• Double Pulse Test:
• First pulse is used to charge up inductor current at desired value.
• First Falling edge = turn-off switching transient
• Second Rising edge = turn-on switching transient
• Parasitic inductance & capacitance• Cause ringing and overshoot in
switching transients losses
Switching Losses Cont.
Switching Energy LossesCurve (Infineon)
0
5
10
15
20
25
30
0 50 100 150 200 250 300 350
Esw
(u
J)
Temperature(K)
20A
10A
3A
20A
10A
3A
Breakdown Voltage
• High voltage applied; near the rated voltage of the device
• Current = 1mA is considered breakdown for the device.
• Gate and source shorted
• 100 kOhms resistor
–+
A
D
G
S
High voltage DC source
Current limiting resistor
Ampere meter
Device under
test (DUT)
Cryo. chamber
Breakdown VoltageResults
• The Drain-Source Voltage• Determined by reverse breakdown
behavior• Reduces as temperature decreases
450
500
550
600
650
700
750
70 120 170 220 270 320
Bre
ak
do
wn
Vo
lta
ge
(V)
Temperature(K)
Conclusion
Efficiency of MOSFET devices improves at cryogenic operation:
• Faster switching w/ less losses
• Allows larger current with less overshooting
• On-state resistance drastically decreases
Acknowledgements
This work was supported primarily by the ERC Program of the National Science Foundation and DOE under NSF Award Number EEC-1041877.
Other US government and industrial sponsors of CURENT research are also gratefully acknowledged.
14
Questions and Answers
15