Power Diodes for Cryogenic Operation PESC 2003 Acapulco, Mexico, June 2003

Power Diodes for Cryogenic

Operation

PESC 2003

Acapulco, Mexico, June 2003

2

R. R. Ward, W. J. Dawson, L. Zhu, R. K. Kirschman

GPD Optoelectronics Corp., Salem, New Hampshire

O. Mueller, M. J. Hennessy, E. K. Mueller

LTE–Low Temperature Electronics, Ballston Lake, New

York

R. L. Patterson, J. E. Dickman

NASA Glenn Research Center, Cleveland, Ohio

A. Hammoud

Dynacs Corp., Cleveland, Ohio

Motivation

4

Cryogenic Power Electronics

• Semiconductor devices (diodes and transistors)

• For Power Management and Actuator Control

• For use down to 30 K = –243°C (and lower)

• Supported by NASA Glenn Research Center

“Very Little of the Solar System

(or the Universe) Is at

Room Temperature.”

6

Solar System Temperatures

Room TemperatureRoom Temperature

7

ApplicationsSpace

• Solar-system exploration

– Reasons: Cold environment, reduced power

– For: Outer planets, cold satellites, asteroids,

interstellar

• Scientific spacecraft/observatories

– Reason: Cryogenic sensors and optics

– For: Motors and actuators

8

ApplicationsDefense, Industry, Commercial

• Medical instruments (MRI)

• Electrical power (superconducting electrical power storage, transmission, distribution)

• Motors/generators (superconducting or cryogenic)

• Magnetic confinement (superconducting or cryogenic)

• High-power amplifiers (cell phone base stations, MRI)

9

ApplicationsDefense, Industry, Commercial

• Medical instruments (MRI)

• Electrical power (superconducting electrical power storage, transmission, distribution)

• Motors/generators (superconducting or cryogenic)

• Magnetic confinement (superconducting or cryogenic)

• High-power amplifiers (cell phone base stations, MRI)

• Reasons: Improved efficiency and reliability, reduced size and mass; many systems already incorporate cryogenics

10

ApplicationsSpace

• Solar-system exploration

– Reasons: Cold environment, reduced power

– For: Outer planets, cold satellites, interstellar

• Scientific spacecraft/observatories

– Reason: Cryogenic sensors and optics

– For: Motors and actuators

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Spacecraft

COLD/HOT ENVIRONMENT

CONVENTIONAL

ELECTRONICS

HEATING/COOLINGSYSTEM

TEMPERATURECONTROL

THERMAL INSULATION

(HEAT STORAGE)

12

Spacecraft

COLD/HOT ENVIRONMENT

CONVENTIONAL

ELECTRONICS

HEATING/COOLINGSYSTEM

TEMPERATURECONTROL

1 3

2

4

4

THERMAL INSULATION

(HEAT STORAGE)

13

Spacecraft

LOW/HIGH TEMP

ELECTRONICS

COLD/HOT ENVIRONMENT

14

“Cold” Spacecraft

• Eliminate heating, thermal control, isolation

• Reduce power, weight, size, cost, complexity

• Improve overall reliability

• Reduce disruption of environment

• Increase mission duration & capability

15

ApplicationsSpace

• Solar-system exploration

– Reasons: Cold environment, reduced power

– For: Outer planets, cold satellites, interstellar

• Scientific spacecraft/observatories

– Reason: Cryogenic sensors and optics

– For: Motors and actuators

Why use Ge?

17

Why Ge Devices?

• Ea,d (Ge) < Ea,d (Si)

18

Why Ge Devices?

• Ea,d (Ge) < Ea,d (Si) Ge can operate at lower T

19

Why Ge Devices?

• Ea,d (Ge) < Ea,d (Si) Lower T for Ge

• Experience with Ge JFETs at cryogenic temperatures

20

Why Ge Devices?

• Ea,d (Ge) < Ea,d (Si) Lower T for Ge

• Experience with Ge JFETs at cryogenic temperatures

• Ge has advantages over other semiconductor materials

Higher mobility than Si (especially at low temp)

– Lower p- n junction forward voltage than Si or III-Vs

21

Mobility Comparison

Data from Madelung, 1991, pp. 18,34.

0

1 104

2 104

3 104

4 104

5 104

80 K 300 K

n-Sip-SiFn-Gep-Ge

np

p

p

p nn

n

Si

Si

Ge

Ge

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Why Ge Devices?

• Ea,d (Ge) < Ea,d (Si) Lower T for Ge

• Experience with Ge JFETs at cryogenic temperatures

• Ge has advantages over other semiconductor materials

– Higher mobility than Si (especially at low temp)

Lower p- n junction forward voltage than Si or III-Vs

23

P-N Junction (Diode) Forward Voltage

0

0.5

1

1.5

0.2 A1 A

2 A4 A

0 40 80 120 160 200 240 280 320

Vf vs T Temperature (K)

Ge

Si

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Why Ge Devices ? (cont’d)

• Applications require operation to 30 - 40 K range

• Ge devices of all types can operate to low cryogenic temperatures (~ 20 K or lower) Diodes can operate to deep cryogenic temperatures

– JFETs can operate to deep cryogenic temperatures (down to few K)

– Bipolar transistors can operate to deep cryogenic temperatures

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Commercial 15-A Ge Diode

0 0.2 0.4 0.6 0.8 1

R7u 4/100/80

R10d 4/100/80

N5u

N6d

M2u

M5d

VH-VL up

VH-VL down

K7d

K10u

VH-VL up

VH-VL down

H13u

H14d0

1

2

3

4

Voltage (V)

77 KRT

40 K 20 K

4 K

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Commercial 15-A Ge Diode

-0.02

-0.01

0

Irev 2(A) downIrev3 (A) upIrev3 (A) upIrev5 (A) downIrev3 (A) downIrev4 (A) upIrev4 (A) downIrev5 (A) upIrev2 (A) upIrev3 (A) down

-100 -80 -60 -40 -20 0

Voltage (V)

4 K

40 K

20 K

77 K

300 K

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Commercial 60-A Ge Diode

0 0.2 0.4 0.6 0.8 1

R2uR3dN10uN11dM12uM13dK18uK19dH21uH21uH22dH23u

0

1

2

3

4

Voltage (V)

77 KRT

40 K

20 K 4 K

28

Commercial 60-A Ge Diode

-0.02

-0.01

0

Rrev4u (A)Rrev5d (A)Rrev6u (A)Rrev7d (A)Nrev8u (A)Nrev9d (A)Mrev14u (A) Mrev15d (A)Krev16u (A)Krev17d (A)Hrev24u (A)Hrev25d (A)

-100 -80 -60 -40 -20 0

Voltage (V)

4 K

40 K

20 K

77 K

300 K

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Why Ge Devices? (cont’d)

• Applications require operation to 30 - 40 K range

• Ge devices of all types can operate to low cryogenic temperatures (~ 20 K or lower)– Diodes can operate to deep cryogenic temperatures

JFETs can operate to deep cryogenic temperatures (down to few K)

– Bipolar transistors can operate to deep cryogenic temperatures

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Field-Effect Transistor Comparison

0

0.5

1

1.5

2

2.5

3

3.5

0 50 100 150 200 250 300

Temperature, T (K)

Si JFET (U310)

Ge JFET

Si JFET (2N4416)

I (300)dss

dss

I (T)

GaAs MESFET (3SK121)

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Ge JFET at 20 K (–253ºC)

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Ge MISFET at 4 K (–273ºC)

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Why Ge Devices? (cont’d)

• Applications require operation to 30 - 40 K range

• Ge devices of all types can operate to low cryogenic temperatures (~ 20 K or lower)– Diodes can operate to deep cryogenic temperatures

– JFETs can operate to deep cryogenic temperatures (down to few K)

Bipolar transistors can operate to deep cryogenic temperatures (down to ~20 K or lower)

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Ge Bipolar Junction Transistor

Zero: upper right Horiz: 0.5 V/div Vert: 1 mA/divIB: 0.02 mA/step at RT, 0.1 mA/step at 4 K

300 K 4 K

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Ge Bipolar Junction Transistor

-100

-80

-60

-40

-20

0-2-1.5-1-0.50

IB = -0.5 mA

2N964-3-1229A,B,C

Collector-emitter voltage, V (V)CE

IB = -2.5 mA

IB = 0

20 K

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Bipolar Junction Transistor Comparison

1

10

100

1000

01020304050

Temperature -1 (1000/K)

SiGe

20 30 50 80 300120

Temperature (K)

Results for New Ge Diodes

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New Planar Ge Cryo Power Diodes

N -

N+ implant

P+ implant Metal

Metal

Guard ring

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New Ge Cryo Power Diodes - Forward

0 0.2 0.4 0.6 0.8 10

2

4

6

8

10

12

Forward Voltage (V)

77 K300 K

40

New Ge Cryo Power Diodes - Forward

0 0.2 0.4 0.6 0.8 10

1

2

3

4

Forward Voltage (V)

120 K

300 K

40 K

20 K

4 K80 K

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Ge Power Diodes - Forward Voltage

0

0.5

1

1.5

0.2 A

0.2 A Si

Vf 0.2 A

Vf 0.2 A

Vf (0.2 A)

Vf (0.2 A)

0 40 80 120 160 200 240 280 320

Temperature (K)

Commercial Ge power diodes

Si power diodes

Ge cryo power diodes (2 thick, 2 thin)

If = 0.2 A

42

Ge Power Diodes - Forward Voltage

0

0.5

1

1.5

2

0 40 80 120 160 200 240 280 320

Temperature (K)

Commercial Ge power diodes

Si power diodes

Ge cryo power diodes (thick)

If = 4 A

Ge cryo power diodes (thick)

Ge cryo power diodes (thin)

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Ge Power Diodes - Reverse Breakdown

0

100

200

300

400

500

600

0 50 100 150 200 250 300

Temperature (K)

18-1-B2b

18-1-D1d

12-1-Aa

Commercial Ge power diodes

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Ge Power Diodes - Reverse Recovery

-12

-8

-4

0

4

8

12

0 200 400 600 800 1000 1200

Time (ns)

77 K

300 K

18-1-AaJune 2003

45

Ge Power Diodes - Reverse Recovery

-12

-8

-4

0

4

8

12

0 200 400 600 800 1000 1200

Time (ns)

77 K

300 K

18-1-B1cJune 2003

46

Ge Power Diodes - Reverse Recovery

0

1

2

3

4

0 2 4 6 8 10 12

Forward Diode Current (A)

77 K

300 K

47

Ge Power Diodes - Reverse Recovery

-12

-8

-4

0

4

8

12

0 200 400 600 800 1000 1200

Time (ns)

77 K

300 K

30-1-C1bJune 2003

48

Ge Power Diodes - Reverse Recovery

-12

-8

-4

0

4

8

12

0 200 400 600 800 1000 1200

Time (ns)

77 K

300 K

30-2-AaJune 2003

49

Summary

• Cryogenic power electronics is needed

for spacecraft going to cold environments

and for space observatories

• Temperatures may be as low as ~30 - 40 K

• We have characterized Ge devices – diodes,

JFETs, and bipolars – at cryogenic temperatures

• Ge devices can operate to deep cryogenic

temperatures – to 20 K and as low as 4 K

• We are developing Ge diodes specifically for

cryogenic applications