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.

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Questions and Answers

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