Compound GaN and SiC, - Transphorm Basis of a $10B LED industry today ... o GaN diode can be built...
Transcript of Compound GaN and SiC, - Transphorm Basis of a $10B LED industry today ... o GaN diode can be built...
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Redefining Energy Efficiency
Compound Semiconductors; GaN and SiC, Separating Fact from Fictionin both Research and Business
Professor Umesh Mishra, Ph.D.
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Compound semiconductors – separating Fact from Fiction
Why do we need a new technology?
What technologies are possible?
What are the relative merits of SiC and GaN?
Performance of GaN vs. SiC
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Coal
45.6%
Nat.Gas24.0%
Nuclear 19.3%
Hydro
6.4%
Wind/Solar 2.1%
Other Renewables
2.6%
US Net Electricity Generation By Source
Motor Drives 51.0%
IT 14.0%
Heating and Cooling 16.0%
Lighting 19.0%
US Net Electricity Consumption
New Solutions Needed to Meet Growing Energy Demands
So what is the issue with Silicon?
Source: EPRI, E‐Source and Exxon MobileSource: EIA (Energy Information Administration)
Conversionlosses
10%
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Industry Power Density Roadmap
Silicon has provided us the pathway for power conversion solutions for several decades but has now reached its physical limits
GaN and SiC open new possibilities
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NYC:50 TWh
SFO:6 TWh
New material options to keep us on the power density roadmap
SiC ‐ established in the market as a high performance diode; released as JFETs and MOSFETs (target application space 1200V)
GaN on Si ‐ high performance solution with a roadmap to low cost for diodes and transistors
GaN on SiC ‐ higher cost solution for applications demanding higher performance with reduced sensitivity to cost
GaN on GaN ‐ early stage of development
Gallium Oxide ‐ very early stage
Diamond ‐ out there
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NYC:50 TWh
SFO:6 TWh
How can a new technology penetrate a market dominated by Silicon?
Have material properties far superior to that of Silicono Not just one product but providing a sustained roadmap to develop a new standard in
power conversion
Provide a solution in an existing market that Si cannot provideo Compound semiconductor devices
Diodes (SiC and GaN)
Transistor (SiC and GaN)
Novel transistor packaging (Quiet Tab™)
Provide a cost advantage in an existing market o System solutions at cost parity or cheaper than Si‐based solution
Reduced components (diode‐free bridge operation)
Efficient high frequency operation
small mechanical and electrical size
Create a new market
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NYC:50 TWh
SFO:6 TWh
How can a new technology penetrate a market dominated by Silicon?
Have material properties far superior to that of Silicono Not just one product but sustained roadmap
Provide a solution in an existing market that Si cannot provideo Compound semiconductor devices
Diodes (SiC and GaN)
Transistor (SiC and GaN)
Novel transistor packaging (Quiet Tab ™)
Provide a cost advantage in an existing market o System solutions at cost parity or cheaper than Si‐based solution
Reduced components (diode‐free bridge operation)
Efficient high frequency operation
small mechanical and electrical size
Create a new market
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Comparing Si, SiC & GaN Semiconductors
GaN and SiC offer:o High breakdown field
GaN offers:o High mobility
SiC offers:o High thermal performance
Si 4H‐SiC GaN
Eg (eV) 1.1 3.2 3.4
Ebk (105 V/cm) 3 21 21
vs (106cm/s) 6 9 12
μ (cm2/Vs) 1000 500* 2000
k (W/mºC) 150 450 130
(Ebkvs/π)2 1 110 140
μEbk2 1 25 98
* Inversion layer: <100; drift 1000
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Why is GaN so remarkable?
o Basis of a $10B LED industry today
o GaN is the wide band gap solution for next generation RF wireless base stations and military RADAR ; chosen over dislocation free SiC MESFETS
Sapphire
6.0
5.0
4.0
3.0
2.0
1.0
3.0 4.0
A1N
GaN
InN
Ener
gy G
ap (
eV)
Lattice Constant (Å)
direct bandgap
indirect bandgap
SiC LED, Laser
RF, Power, High Voltage
(who would have thought?!!)
(who would have thought?!!)
o GaN is a direct bandgap material; It emits light from a dislocated material !
o The tight lattice and no shear stress to move the dislocations makes GaN almost insensitive to dislocations compared to SiC and other compound semiconductors
R = 0
=90°
c – plane
NO shear stress exists for c‐GaN !
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Total Loss of a switch= conduction loss + switching loss
VBDVery High
Breakdown Voltage
Low Leakage
VON
ION
Low RON = VON/IONIMAX
High Maximum Current
VDS
IDS
VOFF
Fast Switching Timesfor Low Switching Loss
ION (dynamic)
No Current collapse
The heart of all power conversion unit is a “SWITCH”
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GaN –Switch gives the lowest conduction loss
Channel with High ns. m Low Ron Low conduction loss Wide band‐gap High Critical Field, High Breakdown Voltage, High Temperature Stability
0 2 0 4 0 6 0 8 0 1 0 0 1 2 0 1 4 0 1 6 0-4
-3
-2
-1
0
1
2
En
erg
y (e
V)
D is ta n c e (n m )
Sp
ecif
ic O
n-R
esis
tan
ce (c
m2)
Breakdown Voltage
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
100 1000 10000
Si
SiC
GaN
Si LimitNCSU ‘97 ACCUFET
On ‘04 SJLDMOS
Yokogawa ‘06 DMOS
Toshiba ‘05 Semi‐SJMOS
Fuji ‘02 SJMOSCREE ‘03 BJT
Purdue ‘98 LDMOS
Kansai ‘00 SIAFET
SiC Limit
Matsushita ‘06 GIT
TransphormTarget
SolutionsAl0.22Ga0.78N/GaN
Limit
Transphorm 2010NIAIST ‘06 IEMOS
SiC MOSFETCREE ‘08 BJT
DC Figure of Merit only
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GaN enables high frequency operation with low switching loss
2x advantage over SiC
14x advantage over Si
5x advantage over Si Superjunction
IGBT Est.12 KHz: >50 Watts100 KHz: > 150 Watts
Tota
l Los
s (A
.U.)
0
100
200
300
400
500
600
700
800
900
1000
1.0E+03 1.0E+04 1.0E+05 1.0E+06 1.0E+07 1.0E+08
Frequency (Hz)
0
1
2
3
4
5
6
7
8
9
10
1.0E+03 1.0E+04
Total Switch
ing L
oss (a.u.)
Frequency (Hz)
Si
SiC
GaN
100 KHz
Tota
l Los
s (A
.U.)
Con
duct
ion
+ S
wit
chin
g Lo
ss
Total Loss minimized for each switching frequency
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0
0.5
1
1.5
2
2.5
3
0 100 200 300 400 500 600 700
Id
Ron
VD (V)
RON(
), I D
(A)
Previous status: Mid 2008
0
0.5
1
1.5
2
2.5
3
3.5
0 100 200 300 400 500 600 700
Id
Ron
VD (V)
RON(
), I D
(A)
Previous status: End 2008
0
0.5
1
1.5
2
2.5
3
0 200 400 600
Id
Ron
Vd (V)
RON(
)
2009
Transphorm Improvements in Dynamic Performance of GaN
Direct relation to performance in real world applications
Major benchmark for success in GaN power devices
Extracted from converter circuit
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NYC:50 TWh
SFO:6 TWh
How can a new technology penetrate a market dominated by Silicon?
Have material properties far superior to that of Silicono Not just one product but sustained roadmap
Provide a solution in an existing market that Si cannot provideo Compound semiconductor devices
Diodes (SiC and GaN)
Transistor (SiC and GaN)
Novel transistor packaging (Quiet Tab ™)
Provide a cost advantage in an existing market o System solutions at cost parity or cheaper than Si‐based solution
Reduced components (diode‐free bridge operation)
Efficient high frequency operation
small mechanical and electrical size
Create a new market
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4A Diode Exampleo Both GaN and SiC diode have lower VF than silicon.
Less conduction loss
o Both GaN and SiC diode has zero minority charge: 0 vs. 62nC (Si)
Less spike & stable high temp operation
o GaN diode can be built on Si substrate
1.47V
SiC Si
2.3V
Tj=125C
1.4V
GaN
GaN‐on‐Si and SiC 600V Diodes Outperform Silicon
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NYC:50 TWh
SFO:6 TWh
How can a new technology penetrate a market dominated by Silicon?
Have material properties far superior to that of Silicono Not just one product but sustained roadmap
Provide a solution in an existing market that Si cannot provideo Compound semiconductor devices
Diodes (SiC and GaN)
Transistor (SiC and GaN)
Novel transistor packaging (Quiet Tab™)
Provide a cost advantage in an existing market o System solutions at cost parity or cheaper than Si‐based solution
Reduced components (diode‐free bridge operation)
Efficient high frequency operation
small mechanical and electrical size
Create a new market
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Advantage: Single chip normally off transistorDisadvantage: Low threshold voltage
GaN Buffer
AlGaN
DielectricS D
GP‐GaN
GaN Buffer
AlGaN
DielectricS DG
Dielectric
P gate depletes the channel
Removing the P layer forms the channel
Advantage: Single chip normally off transistorDisadvantage: Device/ Dielectric not qualified
Junction‐gated HEMTs Channel etch‐through MOSFET
Normally –off HEMTs designs
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HV GaNHEMTLV Si
FET
G
DNormally off
Normally on
Advantage:
o Robust
o High performance
o Compatible with Si drivers
Disadvantage
o Two‐chip solutionSubstrate (SiC or Si)
GaN Buffer
AlGaN Barrier
Source Insulator DrainGate
Device Cell Cross‐section
2DEG
Cascode Approach to achieve normally off
G
D
S
Effective CKT
Normally off
Cascode HEMT implementation
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GaN HEMT
Si CoolMOS(Super junction MOSFET)
Gen‐1 GaN HEMT vs. Si Super Junction MOSFET
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VBD > 1100 V on Si and SiC substrates
Similar leakage with both GaN on SiC and GaN on Silicon
1 nA/mm at >1kV !
< 10% change in Ron under switching
0.1 mA
GaN HEMT on Si vs. GaN HEMT on SiC
GaN‐on‐SiC GaN‐on‐Si
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NYC:50 TWh
SFO:6 TWh
How can a new technology penetrate a market dominated by Silicon?
Have material properties far superior to that of Silicono Not just one product but sustained roadmap
Provide a solution in an existing market that Si cannot provideo Compound semiconductor devices
Diodes (SiC and GaN)
Transistor (SiC and GaN)
Novel transistor packaging (Quiet Tab™)
Provide a cost advantage in an existing market o System solutions at cost parity or cheaper than Si‐based solution
Reduced components (diode‐free bridge operation)
Efficient high frequency operation
small mechanical and electrical size
Create a new market
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Source connected to case for low side switch (A)
Drain connected to case for high side switch (B)o Package body (large capacitor) is always at a DC potential; no switching
o Reduced charging capacitance: lowering charging loss and CM EMI
o GSD has better I‐O isolation than GDS pin out
VCC
L
RL
Q1
V
V
DSG
D
SG
DSG
AC ground
GD
S
Ground
Drain connected to case
Sourceconnected to case
(B)
(A)
High side switch
Low side switch
Quiet Tab™ package made possible by lateral GaN devices
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NYC:50 TWh
SFO:6 TWh
How can a new technology penetrate a market dominated by Silicon?
Have material properties far superior to that of Silicono Not just one product but sustained roadmap
Provide a solution in an existing market that Si cannot provideo Compound semiconductor devices
Diodes (SiC and GaN)
Transistor (SiC and GaN)
Novel transistor packaging (Quiet Tab™)
Provide a cost advantage in an existing market o System solutions at cost parity or cheaper than Si‐based solution
Reduced components (diode‐free bridge operation)
Efficient high frequency operation
small mechanical and electrical size
Create a new market
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LLC DC converter’s improved performance with GaN at 500 kHz
Courtesy: Work done by CPES at Virginia Tech.
• 500kHz for compact power supply design.• Peak efficiency gain by GaN is ~ 1%.• Low‐load efficiency gain (2‐3%)
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Si
System Perform
ance
Device Cost
GaN
SiC
Performance / Price Comparison
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SiC
System Perform
ance
System Cost
Si
Other GaN
Transphorm uniquely enables superior performance at lower cost
GaN SystemAdvantage™
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High frequency design (100kHz‐300kHz) enables compact filter (Lower cost)
Diode‐free Bridge (Lower cost and loss)
ModuleInverter
3‐Phase GaN module & high frequency inverter (motor drive or PV)
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Output power 4.5kw (Single Phase 200V)
Input voltage 60‐400V
Maximum Power Efficiency > 98% (vs. >96.5% with Silicon)
Volume about 10L <18L (existing Silicon based)
93
94
95
96
97
98
99
1000 1500 2000 2500 3000 3500 4000 4500
Output Power[W]
Eff
icie
ncy
[%]
開発品
現製品
Improved EfficiencyIn Major region
Si-PV
GaN-PVGaNPrototype
Silicon
Significant loss reduction
Yaskawa PV converter GaN prototype
40% volume reduction
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So where does this position GaN and SiC?
The view of the future depends upon your point of view
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Market perspective
What Yole Developement showed in 2011 as future view
High‐endsolutions
Middle‐endsolutions
Low‐endsolutions
200 V 600 V 1200 V
SuperJunctionMOSFET
SuperJunctionMOSFET
SuperJunctionMOSFET
SuperJunctionMOSFET
SiCGaN
GaN Silicon
Silicon Silicon
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Market perspective
A Super Junction supplier’s view of future
High‐endsolutions
Middle‐endsolutions
Low‐endsolutions
200 V 600 V 1200 V
Super Junction MOSFET
SuperJunctionMOSFET
Super JunctionMOSFET
Super Junction MOSFET
SiC
GaN
GaN Silicon
SiliconSilicon
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Market perspective
A SiC supplier’s view of future
High‐endsolutions
Middle‐endsolutions
Low‐endsolutions
200 V 600 V 1200 V
SuperJunctionMOSFET
SuperJunctionMOSFET
SiC
GaN
Silicon
Silicon Silicon
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Market perspective
Now that 600 V GaN on Silicon is Qualified, a GaN solution supplier’s view for future
High‐endsolutions
Middle‐endsolutions
Low‐endsolutions
200 V 600 V 1200 V
SuperJunctionMOSFET
SiCGaN
GaN GaNSuperJunctionMOSFET
GaNSilicon