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Power Semiconductor Devices
for
Low-Temperature Environments
Space Power Workshop 2004
21 April 2004, Manhattan Beach, California
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
MTECH Laboratories, Ballston Lake, New York
R. L. Patterson, J. E. Dickman
NASA Glenn Research Center, Cleveland, Ohio
A. Hammoud
QSS Group Inc., Cleveland, Ohio
Supported by NASA Glenn Research Center and ONR/DARPA
3
Outline
Why low-temperature electronics for space?
Semiconductor materials options
Development program
Designs and results
Diodes: Ge & SiGe
FETs: Ge MISFETs, Ge JFETs & Ge SITs
Bipolars: Ge BJTs & SiGe HBTs
Summary
Future
4
Outline
Why low-temperature electronics for space?
Semiconductor materials options
Development program
Designs and results
Diodes: Ge & SiGe
FETs: Ge MISFETs, Ge JFETs & Ge SITs
Bipolars: Ge BJTs & SiGe HBTs
Summary
Future
5
Temperatures for Spacecraft
TemperatureBody or location
(°C) (K)
Phobos (satellite of Mars)a –112 160
Moona –150 120
Eros (near-Earth asteroid)a –150 120
Jupiter orbitb –150 120
Europa (satellite of Jupiter) –160 110
Saturn orbitb –180 90
Titan (satellite of Saturn) –180 90
Uranus orbitb –210 60
Neptune orbitb –220 50
Pluto orbitb –230 44
Triton (satellite of Neptune) –235 38
Interstellar spaceb <–233 <40
a“Nighttime” temperature. bBlack-body equilibrium temperature.
6
Solar System Temperatures
7
Benefits of Using Low-Temp Electronics
• Reduce mass & volume
• Reduce power requirements
• Reduce spacecraft complexity
• Reduce disruption of environment
• Increase operating/mission time
• Increase overall reliability
8
Outline
Why low-temperature electronics for space?
Semiconductor materials options
Development program
Designs and results
Diodes: Ge & SiGe
FETs: Ge MISFETs, Ge JFETs & Ge SITs
Bipolars: Ge BJTs & SiGe HBTs
Summary
Future
9
Semiconductor Materials Comparison
Parameter Want Si Ge SiGe
P-N junction forward V Low High Low Med
Reverse breakdown V High High (Low) High?
Mobility at cryo temps High Med High High
Switching speed High Adequate Adequate High
Operating temp range RT to ~20 K RT to ~100 K(due to BJT)
RT to < 20 K RT to < 4 K
Gate dielectric for MOS High quality,easily produced
Yes Difficult Yes
Compatibility withexisting Si fabrication
High High Low High
Bold = Exhibits desirable characteristic
10
Outline
Why low-temperature electronics for space?
Semiconductor materials options
Development program
Designs and results
Diodes: Ge & SiGe
FETs: Ge MISFETs, Ge JFETs & Ge SITs
Bipolars: Ge BJTs & SiGe HBTs
Summary
Future
11
Development Program
• Develop semiconductor devices: diodes and transistors
• Specifically designed for low temperatures
• For use down to 30 K (~ –240°C) and lower
• For spacecraft Power Management and Actuator Control
12
Outline
Why low-temperature electronics for space?
Semiconductor materials options
Development program
Designs and results
Diodes: Ge & SiGe
FETs: Ge MISFETs, Ge JFETs & Ge SITs
Bipolars: Ge BJTs & SiGe HBTs
Summary
Future
13
Ge Low-Temperature Power DiodesP- - N Bulk Design
N– ( )
N+ implant
P+ implant Metal
Metal
Guard ring(s)
14
Ge LT Power Diodes - Forward
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
15
Ge LT Power Diodes - Forward
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)
16
Ge LT Power Diodes - Forward I-V
17
Ge LT Power Diode - Forward I-V
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 - 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
19
-12
-8
-4
0
4
8
12
0 200 400 600 800 1000 1200
Time (ns)
77 K
300 K
30-1-C1bJune 2003
Ge Power Diodes - Reverse Recovery
20
-12
-8
-4
0
4
8
12
0 200 400 600 800 1000 1200
Time (ns)
77 K
300 K
30-2-AaJune 2003
Ge Power Diodes - Reverse Recovery
21
0
1
2
3
4
0 2 4 6 8 10 12
Forward Diode Current (A)
77 K
300 K
Ge Power Diodes - Reverse Recovery
22
Outline
Why low-temperature electronics for space?
Semiconductor materials options
Development program
Designs and results
Diodes: Ge & SiGe
FETs: Ge MISFETs, Ge JFETs & Ge SITs
Bipolars: Ge BJTs & SiGe HBTs
Summary
Future
23
SiGe LT Power Diodes - Design
(N+ implant)
P+ SiGe Metal
Metal
N– Si epi
N+ Si
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SiGe vs Si Power Diodes - Forward
0
20
40
60
80
100
I (mA)Ifor (mA) RTIf RT (mA)If (mA)
0 0.2 0.4 0.6 0.8 1 1.2
Si
Vfor
(V)
300 K
2ASiGe: 1A
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SiGe vs Si Power Diodes - Forward
0
20
40
60
80
100
I (mA)Ifor (mA) LNIf LN (mA)If (mA)
0 0.2 0.4 0.6 0.8 1 1.2
Vfor
(V)
77 K
Si2ASiGe: 1A
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SiGe LT Power Diodes - Forward
0
0.5
1
1.5
0.2 A0.2 A SiVf 0.2 AVf 0.2 A
Vf (0.2 A)Vf (0.2 A)Vf @ 0.2 A (V)
0 40 80 120 160 200 240 280 320
Temperature (K)
Ge commercial
SiGe
If = 0.2 A
SiGe
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SiGe LT Power Diodes - Forward
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SiGe LT Power Diodes - Forward
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SiGe LT Power Diodes - Reverse
-0.02
0
0.02
0.04
0.06
0.08
0.1
-100 -80 -60 -40 -20 0 20 40
Voltage (V)
SiGe/SiDiodes300 K
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SiGe LT Power Diodes - Reverse
-0.02
0
0.02
0.04
0.06
0.08
0.1
-100 -80 -60 -40 -20 0 20 40
Voltage (V)
SiGe/SiDiodes77 K
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SiGe LT Power Diodes - Reverse Recovery
-4
-2
0
2
4
6
8
10
12
0.0 0.2 0.4 0.6 0.8 1.0
Dio
de
Cu
rren
t (A
)
Time (µs)
300 K
77 K
SiGe-1B
Silicon-Germanium Diode
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SiGe LT Power Diodes - Reverse Recovery
-4
-2
0
2
4
6
8
10
12
0.0 0.2 0.4 0.6 0.8 1.0
Dio
de
Cu
rren
t (A
)
Time (µs)
300 K
77 K
GPD SiGe-2A
Silicon-Germanium Diode
33
Outline
Why low-temperature electronics for space?
Semiconductor materials options
Development program
Designs and results
Diodes: Ge & SiGe
FETs: Ge MISFETs, Ge JFETs & Ge SITs
Bipolars: Ge BJTs & SiGe HBTs
Summary
Future
34
Ge LT Power JFET or MISFET
~1.8 mm
G
S
D
S
G
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Lateral Ge MISFET Design
Substrate contact
Source Gate
P+ implant
P substrate
Gate dielectric
N+ implant
Drain
36
Ge Power MISFET at +20°C
20 V
1 A ΔVGS = 1 V/step
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Ge Power MISFET at –196°C (77 K)
20 V
1 A ΔVGS = 1 V/step
38
Ge Power MISFET at –269°C (4 K)
20 V
1 A ΔVGS = 1 V/step
39
Ge MISFET Switching - 50 kHz
0
5
10
15
20
-0.05
0
0.05
0.1
0.15
0 10 20 30 40 50Time (s)
300 K
0
5
10
15
20
-0.05
0
0.05
0.1
0.15
0 10 20 30 40 50Time (s)
77 K
0
5
10
15
20
-0.05
0
0.05
0.1
0.15
0 10 20 30 40 50Time (s)
4 K
~30 Load
40
Ge MISFET Switching - 5 MHz
~30 Load
0
5
10
15
20
-0.05
0
0.05
0.1
0.15
0 100 200 300 400 500Time (ns)
300 K
0
5
10
15
20
-0.05
0
0.05
0.1
0.15
0 100 200 300 400 500Time (ns)
77 K
0
5
10
15
20
-0.05
0
0.05
0.1
0.15
0 100 200 300 400 500Time (ns)
4 K
41
Outline
Why low-temperature electronics for space?
Semiconductor materials options
Development program
Designs and results
Diodes: Ge & SiGe
FETs: Ge MISFETs, Ge JFETs & Ge SITs
Bipolars: Ge BJTs & SiGe HBTs
Summary
Future
42
Ge JFET Cross-Section (n-channel)
Back gate contact
SourceFront gate
P+ implant
P+ substrate
N epitaxial layer
N+ implant
Drain
P+ implant
43
Power Ge JFET at +20°C
10 V
2 A ΔVGS = 1 V/step
44
Power Ge JFET at –196°C (77 K)
10 V
2 A ΔVGS = 1 V/step
45
Power Ge JFET at –269°C (4 K)
10 V
2 A ΔVGS = 1 V/step
46
Another Power Ge JFET at –253°C (20 K)
10 V
1 A ΔVGS = 1 V/step
47
Power Ge JFET at +20°C
50 V
1 A ΔVGS = 1 V/step
48
Power Ge JFET at –196°C (77 K)
50 V
1 A ΔVGS = 1 V/step
49
Power Ge JFET at –269°C (4 K)
50 V
1 A ΔVGS = 1 V/step
50
Outline
Why low-temperature electronics for space?
Semiconductor materials options
Development program
Designs and results
Diodes: Ge & SiGe
FETs: Ge MISFETs, Ge JFETs & Ge SITs
Bipolars: Ge BJTs & SiGe HBTs
Summary
Future
51
Ge SIT (Static Induction Transistor)
Drain
SourceGate
N+ implant
N– substrateP implantN+ implant
52
Ge SIT - FET-Like Region
53
Ge SIT - Triode-Like Region
54
Outline
Why low-temperature electronics for space?
Semiconductor materials options
Development program
Designs and results
Diodes: Ge & SiGe
FETs: Ge MISFETs, Ge JFETs & Ge SITs
Bipolars: Ge BJTs & SiGe HBTs
Summary
Future
55
Ge Bipolar - Double-Implant
Collector
Base Emitter
N+ implant
N– substrate
P implant
N+ implant
56
Ge BJT at +20°C
10 V
0.1 A ΔIB = 0.5 mA/step
57
Ge BJT at –196°C (77 K)
10 V
0.1 A ΔIB = 1 mA/step
58
Ge and Si Bipolar Comparison
1
10
100
1000
01020304050
Temperature -1 (1000/K)
SiGe
20 30 50 80 300120
Temperature (K)
59
Outline
Why low-temperature electronics for space?
Semiconductor materials options
Development program
Designs and results
Diodes: Ge & SiGe
FETs: Ge MISFETs, Ge JFETs & Ge SITs
Bipolars: Ge BJTs & SiGe HBTs
Summary
Future
60
SiGe HBT (Heterojunction Bipolar Transistor)
~0.5 μm n+ Si
~0.4 μm p SiGe
~20 μm n– Si
Emitter contact
~300 μm n+ Si
Collector contact
Base contact
61
SiGe HBT at +20°C
20 V
0.2 A ΔIB = 1 mA/step
62
SiGe HBT at –196°C (77 K)
50 V
ΔIB = 0.5 mA/step0.2 A
63
Outline
Why low-temperature electronics for space?
Semiconductor materials options
Development program
Designs and results
Diodes: Ge & SiGe
FETs: Ge MISFETs, Ge JFETs & Ge SITs
Bipolars: Ge BJTs & SiGe HBTs
Summary
Future
64
Summary
• Electronics capable of low-temperature operation will be
important for spacecraft (cold environments and space
observatories)
• We have been developing semiconductor devices for
operation down to ~20 K (~ –250°C)
• We are basing the devices on Ge and SiGe
• We have developed Ge low-temperature power diodes,
junction field-effect transistors (JFETs), and metal-insulator-
semiconductor field-effect transistors (MISFETs)
• We are in process of developing SiGe low-temperature power
diodes, metal-insulator-semiconductor field-effect transistors
(MISFETs), and heterostructure bipolar transistors (HBTs)
65
Outline
Why low-temperature electronics for space?
Semiconductor materials options
Development program
Designs and results
Diodes: Ge & SiGe
FETs: Ge MISFETs, Ge JFETs & Ge SITs
Bipolars: Ge BJTs & SiGe HBTs
Summary
Future
66
Future
• Continue to develop low-temperature power
SiGe diodes, SiGe bipolar transistors,
SiGe MOS field-effect transistors
• Investigate low-temperature power SiGe IGBTs
• Proposed development of low-temperature power
thyristors (SCRs)
