Novel SiGe Semiconductor Novel SiGe Semiconductor

Devices forDevices for

Cryogenic Power ElectronicsCryogenic Power Electronics

ICMC/CEC August-September 2005Keystone, Colorado

2

Outline

Authors and Sponsors

Goals and Applications

Why SiGe?

Designs and results

SiGe heterojunction diodes

Cryogenic power converter

Summary

3

Outline

Authors and Sponsors

Goals and Applications

Why SiGe?

Designs and results

SiGe heterojunction diodes

Cryogenic power converter

Summary

4

Rufus Ward, Bill Dawson, Lijun Zhu, Randall Kirschman

GPD Optoelectronics Corp., Salem, New Hampshire

Guofu Niu, Mark Nelms

Auburn University, Dept. of Electrical and Computer

Engineering, Auburn, Alabama

Mike Hennessy, Eduard Mueller, Otward Mueller,

MTECH Labs./LTE, Ballston Lake, New York

Authors

GPD Optoelectronics GPD Optoelectronics CorporationCorporation

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Sponsors

US Office of Naval Research

US Army Aviation and Missiles Command

Defense Advanced Research Projects Agency

6

Outline

Authors and Sponsors

Goals and Applications

Why SiGe?

Designs and results

SiGe heterojunction diodes

Cryogenic power converter

Summary

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Goals

• Develop SiGe devices for cryogenic power use

• Exhibit the performance advantages of SiGe versus Si for cryogenic power

• Specifically:

– Demonstrate prototype SiGe power diodes for cryogenic operation

– Demonstrate a 100-W power conversion circuit, to deep cryogenic temperatures.

– To ~ 55 K

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Application Areas

• For power management and distribution (PMAD)

– Power conversion for storage and distribution

– Power conversion for motors/generators

– E.g. “All-Electric” ship

• DoD applications

– Cryogenic systems for ships and aerospace

– Propulsion systems

– Superconducting or cryogenic

– Temperature ~ 60 – 65 K (for HTSC)

9

Outline

Authors and Sponsors

Goals and Applications

Why SiGe?

Designs and results

SiGe heterojunction diodes

Cryogenic power converter

Summary

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Why SiGe?• Can incorporate desirable characteristics of both Si and Ge

• Can optimize devices for cryogenic applications by selective use of Si and SiGe

• SiGe provides additional flexibility through band-gap engineering (% of Ge, grading) and selective placement

• All device types work at cryogenic temperatures–

Diodes

– Field-effect transistors– Bipolar transistors– Combinations of above (IGBTs, thyristors, ...)

• Devices can operate at all cryogenic temperatures (as low as ~ 1 K if required)

• Compatible with conventional Si processing

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Outline

Authors and Sponsors

Goals and Applications

Why SiGe?

Designs and results

SiGe heterojunction diodes

Cryogenic power converter

Summary

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SiGe Diode Simulations

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SiGe Heterostructure Diode

(N+ backside implant)

SiGe epilayer P+ Frontside contact

Backside contact

Si substrate N+

Si epilayer N–

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Epilayer(s)

Wafer ID Si substrate thickness(es) andcomposition

dopant(s) doping concentrations(s)(cm–3)

First series (6 types)

50584G-J 22.1 nm, 19.5% Ge n-type, phosphorus 1.8e19

50583G-J 21.8 nm, 20.5% Ge p-type, boron 1.6e19

50582F-J

n-type, 10-50 ? -cm

1e14 cm–3

21.2 nm, 20.1% Ge undoped undoped

50584A-F 22.1 nm, 19.5% Ge n-type, phosphorus 1.8e19

50583A-F 21.8 nm, 20.5% Ge p-type, boron 1.6e19

50582A-E

p-type, 10-50 ? -cm

8e14 cm–3

21.2 nm, 20.1% Ge undoped undoped

Second series (4 types)

1A70305

n-type, 1e19 cm-3 20.3 μm Si30 nm, 31% Ge

n-type, phosphorusp-type, boron

7e146.5e18

1B70307

p-type, 1e19 cm-3 20.3 μm Si30 nm, 31% Ge

p-type, boronn-type, phosphorus

5.2e141.1e19

2A70295/7

n-type, 1e19 cm-3 20.3 μm Si206 nm, 8% Ge

n-type, phosphorusp-type, boron

6e141.5e19

(3A*)70298 n-type, 1e19 cm-3

20.3 μm Si300? nm, 5.3% Ge

500? nm

n-type, phosphorusp-type, boronp-type, boron

6e143e17

1.3e19

Third series (4 types)

21** Si, n+ > 3e19* 20 μm Si n-type uniform doping, 2e14 to 6e14

22** Si, n+ > 3e19* 20 μm Si n-typegraded dopant concentration,

~1e15 at substrate to ~2e14 atSiGe epi layer

23** Si, n+ > 3e19*

20 μm SiGe, gradedGe fraction: 0% Ge atsubstrate to 20% atSiGe p+ epi layer

n-type uniform doping, 2e14 to 6e14

24*** Si, n+ > 3e19* Si, 20 μm n-typeuniform doping: 2e14 to 6e14Si,

thickness same as above(~100 nm), p+ 1e19

*This wafer was specified for another type of device, but was also used for diodes.

**Epi layer 2: SiGe, 20%Ge, maximize thickness (~100 nm), p+ 1e19.

***Epi layer 2: Si, thickness same as above (~100 nm), p+ 1e19.

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SiGe vs Si Diode Characteristics

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SiGe vs Si Forward Voltage

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SiGe vs Si and SiC Forward Voltage

0

200

400

600

800

1000

1200

1400

-200 -150 -100 -50 0 50

Temperature (degrees C)

Fo

rwa

rd D

rop

(m

V)

SiCSiGeSi #1Si #2Si #3

Univ. of Auburn measurements.

SiGe

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SiGe vs Si Reverse Recovery

Univ. of Auburn measurements.

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SiGe vs Si Reverse Recovery

Univ. of Auburn measurements.

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SiGe vs Si Reverse Recovery

MTECH Labs. measurements.

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SiGe vs Si Reverse Recovery

MTECH Labs. measurements.

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Outline

Authors and Sponsors

Goals and Applications

Why SiGe?

Designs and results

SiGe heterojunction diodes

Cryogenic power converter

Summary

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SiGe Boost Converter

Outputcapacitor

SiGe diode

Switching pulse

Inductor

LoadSiGe HBT

+

–

Inputcapacitor

24 V in 48 V out

~20 – 300 K

Optoisolator

Drivecircuit

Pulsegenerator

Power supply

+

–

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SiGe 100 W Cryo Boost Converter100 kHz, 24 V in, 48 V out

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SiGe 100 W Cryo Boost ConverterBackside

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Cryostat for Measuring 100 W Circuits

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100 W SiGe Power Converter in Cryostat

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SiGe vs Si diodes in 100 W Cryo Boost Converter

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Outline

Authors and Sponsors

Goals and Applications

Why SiGe?

Designs and results

SiGe heterojunction diodes

Cryogenic power converter

Summary

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Summary• Cryogenic power conversion is of interest for a range of

applications within DoD and elsewhere.

• For cryogenic power conversion, SiGe devices are potentially superior to devices based on Si or Ge.

• We are developing SiGe semiconductor devices for cryogenic power applications.

• We have simulated SiGe diodes: results indicate improvements over Si diodes and have guided design.

• We have designed, fabricated, and used SiGe diodes (and HBTs) in power converters operating at cryogenic temperatures and converting >100 W.

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Outline

Authors and Sponsors

Goals and Applications

Why SiGe?

Designs and results

SiGe heterojunction diodes

Cryogenic power converter

Summary