A classification of power
semiconductor devices
Power Electronic
LOGO
Can be categorised into three groups:
– Uncontrolled: Diode
– Fully controlled: Power transistors e.g. (BJT, MOSFET,
IGBT, GTO, IGCT….)
–Semi-controlled: Thyristor (SCR), Triac…
Chapter 1 Power
semiconductor devices
ThS: TRẦN VĂN HÙNG
Email: tranvanhung@iuh.edu.vn
E-Learning: Trần Văn Hùng
ocw.fet.iuh.edu.vn
– Other new power electronic devices: SIT, SITH,
MCT, IGCT, Power electronic devices based
on wide band gap semiconductor material
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1
SCR (Silicon Controlled
Rectifier)
Semi-controlled: Thyristor
(SCR), Triac
History
1
2
3
SCR
TRIAC
GTO
(Silicon
Controlled
Rectifier)
(Triode
Alternative
Current)
(Gate turn
– off
Thyristor)
 Another name: SCR—silicon controlled
rectifier
 Thyristor Opened the power electronics
area
 1956, invention, Bell Laboratories
 1957, development of the 1st product, GE
 1958, 1st commercialized product, GE
 Thyristor replaced vacuum devices in almost every
power processing area.
 Still in use in very high power situation.
Thyristor still has the highest powerhandling capability.
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SCR (Silicon Controlled
Rectifier)
SCR (Silicon Controlled
Rectifier)
Appearance and symbol of thyristor
Device Rating
V (V)
12000
Appearance
12000V/1500A
(M itsubishi)
SCR
27M VA
SCR:
GTO/GCT: 36M VA
6M VA
IGBT:
10000
6500V/600A
(Eupec)
8000
Symbol
Cathode
Gate
Anode
7500V/1650A
(Eupec)
6000V/3000A
(ABB)
6500V/4200A
(ABB)
6000V/6000A
(M itsubishi)
6000
6500V/1500A
(M itsubishi)
GTO/GCT
4800V
5000A
(Westcode)
3300V/1200A
(Eupec)
4000
4500V/900A
(Mitsubishi)
2000
2500V/1800A
(Fuji)
1700V/3600A
(Eupec)
IGBT
0
0
1000
2000
3000
4000
5
SCR (Silicon Controlled
Rectifier)
5000
6000 I (A)
6
SCR (Silicon Controlled
Rectifier)
Structure of thyristor
• Structure
• Sy
- Thicker n- layer gives higher voltage blocking
capability to the device.
- The forward voltage at which the device turns
on decreases with increase in gate current.
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SCR (Silicon Controlled
Rectifier)
SCR (Silicon Controlled
Rectifier)
J1
Structure and equivalent circuit of thyristor
• Structure
• Equivalent circuit
J1
J2
n1
p1 n1
A
iAK
J3
p2
n2
K
J3
A
p1
J2
p2
n2
K
iAG
G
A
J2
J1
+
SCR1
• IA and IG
G
p1
n1
J3 iAK
p2 n2
2N3668
G
+
9
K
iGK
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SCR (Silicon Controlled
Rectifier)
Physics of thyristor operation
 Equivalent circuit: A pnp
transistor and an npn
transistor interconnected
together.
 Positive feedback
 Trigger
 Can not be turned off by
control signal
SCR (Silicon Controlled
Rectifier)
Quantitative description of thyristor operation
Ic1=1 IA + ICBO1
Ic2=2 IK + ICBO2
IK=IA+IG
IA=Ic1+Ic2
2IG  ICBO1 ICBO2
 IA 
1 (1 2 )
When IG=0, 12 is small.
When IG>0, 12 will approach 1, and IA will
be very large.
 Half-controllable
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SCR (Silicon Controlled
Rectifier)
Factors Causing Turn ON of SCR
 High voltage across anode and cathode
avalanche breakdown
 High rising rate of anode voltage du/dt
too high
 High junction temperature
 Light activation
SCR (Silicon Controlled
Rectifier)
How to Turn Off SCR?
 Gate current has no control over the SCR
after it turns ON.
 IA should be reduced below the holding value
IH in order to make (α1+α2) → 0 to stop the
internal regenerative action to turn OFF the
device.
 After IA drops to zero, the device should be
reverse biased for a duration tq > tOFF where
tOFF is known as the device turn OFF time and
tq is known as the circuit turn-off time.
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SCR (Silicon Controlled
Rectifier)
Static characteristics of thyristor
IA
forward
conducting
increasing IG
IH
U RSM U RRM
reverse
blocking
O
I G2
forward
blocking
I G= 0
I G1
U DRM
U bo
U DSM
avalanche
breakdown
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 Blocking when reverse
biased, no matter if there is
gate current applied
 Conducting only when
forward biased and there is
triggering current applied to
the gate
 Once triggered on, will be
latched on conducting even
U Ak
when the gate current is no
longer applied
 Turning off: decreasing
current to be near zero with
the effect of external power
circuit
 Gate I-V characteristics
SCR (Silicon Controlled
Rectifier)
Switching characteristics of thyristor
iA
100%
90%
10%
0 td
uAK
 Turn-on transient
 Delay time td
 Rise time tr
 Turn-on time tgt
t  Turn-off transient
tr
IRM
t
O
trr
URRM t
gr
16
 Reverse recovery
time trr
 Forward recovery
time tgr
 Turn-off time tq
SCR (Silicon Controlled
Rectifier)
Snubber Circuit for SCR
Specifications of thyristor
 Peak repetitive forward blocking voltage UDRM
 Peak repetitive reverse blocking voltage URRM
 Peak on-state voltage UTM
 Average on-state current IT(AV)
 Holding current IH
 Latching up current IL
 Peak forward surge current ITSM
 du/dt
 di/dt
17
SCR (Silicon Controlled
Rectifier)
Switching states
19
18
SCR (Silicon Controlled
Rectifier)
Shape of SCR
20
SCR (Silicon Controlled
Rectifier)
TRIAC (Triode Alternative
Current)
The family of thyristors
Shape of SCR
I
 Fast switching thyristor—FST
 Triode AC switch—TRIAC
(Bi-directional triode
T1
thyristor)
IG=0
O
G
U
T2
Reverse-conducting thyristor
K
RCT
Light-triggered (activited) thyristor
LTT
A
K
G
G
G
A
K
A
21
TRIAC (Triode Alternative
Current)
22
TRIAC (Triode Alternative
Current)
• Structure
• Symbol
N1
MT2
MT2
MT2
MT2
P1
MT2
P
N
G
N2
N3
Shorting of p1 region to n3 region due to MT2 metal
contact, and the p2 region to the n2 region due to MT1
metal contact results in two anti-parallel SCR structures:
p1n1p2n2 and p2 n1p1n3.
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P2
G
N4
MT1
G
P
N
MT1
24
G
G
P
MT1
MT2
N
MT1
N
G
MT1
P
MT1
TRIAC (Triode Alternative
Current)
TRIAC (Triode Alternative
Current)
• Structure
The basic operation of Triac
• Equivalent circuit
MT2
N1
MT2
N1
P1
P2
N1
P1
N2
N2
N3
MT2
N3
N4 G
MT1
N1
P1
N2
G
P2
N3
N4
P2
IG <0
MT2 >MT1
P1
N2
G
N3
N4
MT1
MT1
IG >0
MT2 >MT1
MT2
P2
G
N4
MT1
IG <0
MT1 >MT2
IG >0
MT1 >MT2
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TRIAC (Triode Alternative
Current)
TRIAC (Triode Alternative
Current)
• Equivalent circuit
T
T1
U1
U1
Z
T2
u
u
i
1
iG1
I-V characteristics of Triac
27

3
2
iG2
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Z
TRIAC (Triode Alternative
Current)
TRIAC (Triode Alternative
Current)
Shape of Triac
Shape of Triac
MT1
2N6346
MT1
MT2
MT2
G
MT1
G
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Limitations of TRIAC as
Compared to SCRs
• Has lower dv/dt rating.
• Requires well designed R-C snubber connected
across it to limit dv/dt.
• Has longer turn-off time.
• Has lower power handling capability.
• Typically used in small motor speed regulators,
temperature control, illumination control, liquid
level control, phase control circuits, power
switches.
• Cannot be used in A.C. systems of frequency
more than 400 Hz.
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30
GTO
(Gate turn – off Thyristor)
GTO: Typical fully-controlled devices
Symbol
Structure
G
K
N2
K
G
P2
G
N2
N1
P1
A
a)
b)
 Major difference from conventional thyristor:
The gate and cathode structures are highly
integrated, with various types of geometric forms
being used to layout the gates and cathodes.
32
GTO
GTO
(Gate turn – off Thyristor)
(Gate turn – off Thyristor)
GTO: Typical fully-controlled devices
• Current distribution in a GTO
Structure
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34
GTO
GTO
(Gate turn – off Thyristor)
(Gate turn – off Thyristor)
Physics of GTO operation
GTO: Typical fully-controlled devices
 The basic operation of GTO is
the same as that of the
conventional thyristor.
Basic Structure
A
IA
PNP
V1
I
Ic1
G G
S
EG
NPN
Ic2
V2
IK
K
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 The principal differences lie in
the modifications in the
structure to achieve gate turnoff capability.
EA
 Large 2
 1+2 is just a little larger than
the critical value 1.
 Short distance from gate to
cathode makes it possible to
drive current out of gate.
R
36
GTO
GTO
(Gate turn – off Thyristor)
(Gate turn – off Thyristor)
Characteristics of GTO
GTO: Turning ON
 Static characteristics
 Identical to conventional thyristor in the forward direction
 Rather low reverse breakdown voltage (20-30V)
 Switching characteristics
iG
O
GTO: Turning off
t
iA
IA
90%IA
10%IA
0
td
t0
tr
t1
ts
t2
t3
37
t4
tt
t5
t6
t
38
GTO
GTO
(Gate turn – off Thyristor)
(Gate turn – off Thyristor)
Specifications of GTO
tf
• Switching Characteristics
vT , iT
 Maximum controllable anode current IATO
0 .9 I D
0 .9V D
meanings as those of conventional thyristor.
 Specifications different from thyristor’s
iT
vT
 Most GTO specifications have the same
ID
VD
0 . 1V D
0 .1I D
t don t r
iG
 Current turn-off gain βoff
t tail
t doff
tf
diG 1 / dt
I G 1M
 Turn-on time ton
0
0 . 1I G 1 M
 Turn-off time toff
40
iT
iG
vT
t
0 .1I G 2 M
diG 2 / dt
39
t
0
IG 2M
GTO
GTO
(Gate turn – off Thyristor)
(Gate turn – off Thyristor)
Control Characteristics of GTO
GTO Compared with SCR
• GTO can be turned on by applying a positive gate current
pulse and turned off by applying a negative gate current
pulse.
• To prevent unwanted turn-off during transients, it is
recommended to apply a low value of continuous positive
gate current as long as GTO has to be kept on.
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GTO
GTO
(Gate turn – off Thyristor)
(Gate turn – off Thyristor)
Shape of GTO
Shape of GTO
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Other new power electronic
devices
SIT (Static induction transistor)
Static induction transistor—SIT
1
2
3
SIT (Static induction transistor)
SITH (Static induction thyristor)
 Another name: power junction field
effect transistor—power JFET
MCT (MOS controlled thyristor)
4
IGCT (Integrated gate-commutated thyristor)
5
Power electronic devices based on wide
band gap semiconductor material
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SIT (Static induction transistor)
Static induction transistor—SIT
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SITH (Static induction thyristor)
Static induction thyristor—SITH
other names
 Field controlled thyristor—FCT
 Field controlled diode
Features





Majority-carrier device
Fast switching, comparable to power MOSFET
Higher power-handling capability than power MOSFET
Higher conduction losses than power MOSFET
Normally-on device, not convenient (could be made
normally-off but with even higher on-state losses)
SIT
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SITH
48
SITH (Static induction thyristor)
Static induction thyristor—SITH
Features
 Minority-carrier device, a JFET structure with an
additional injecting layer
 Power-handling capability similar to GTO
 Faster switching speeds than GTO
 Normally-on device, not convenient (could be made
normally-off but with even higher on-state losses)
MCT (MOS controlled thyristor)
MOS controlled thyristor—MCT
 Essentially a MCT with integrated MOSdriven gates controlling both turn-on and
turn-off that potentially will significantly
simplify the design of circuits using GTO.
 The difficulty is how to design a MCT that can
be turned on and turned off equally well.
 Once believed as the most promising device,
but still not commercialized in a large scale.
The future remains uncertain.
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MCT (MOS controlled thyristor)
MCT (MOS controlled thyristor)
Structure N-MCT
Turn OFF
MOSFET
Turn ON
MOSFET
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MCT (MOS controlled thyristor)
Structure P-MCT
MCT (MOS controlled thyristor)
Appearance
53
IGCT (Integrated gatecommutated thyristor)
Integrated gate-commutated thyristor —
IGCT
54
IGCT (Integrated gatecommutated thyristor)
Structure
Symbol
 Introduced in 1997 by ABB
A
 Actually the close packaging of GTO and the
gate drive circuit with multiple MOSFETs in
parallel providing the gate currents
 Short name: GCT
G
G
switching speed are superior to GTO
 Competing with IGBT and other new devices
to replace GTO
55
K
K
 Conduction drop, gate driver loss, and
56
IGCT (Integrated gatecommutated thyristor)
IGCT (Integrated gatecommutated thyristor)
• Equivalent circuit
Appearance
Turn-on
Q1
C1
Cn
Qn
10V - 5A
GCT Gate
Control
Q1
Qn
20V - 6 A
C1
Cn
C2
50,000 µF
GCT Cathode
Turn-off
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IGCT (Integrated gatecommutated thyristor)
Power electronic devices based on wide band
gap semiconductor material
• Switching Characteristics
vT , iT
E4
iT
vT
0 .9 I D
0 . 9V D
ID
VD
t don
Band
gap
E3
0 .4 I D
0 . 1V D
0
iG
 Energy band and band gap
t
tr
t doff
iT
tf
iG
iG
E2
vT
diG 1 / dt
t
0
vG
diG 2 / dt
vG
E1
Energy levels of an independent atom (left )
and energy bands of an atom in a crystal
structure
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Power electronic devices based on wide band
gap semiconductor material
Review of device classifications
Properties of semiconductor materials with potential for power devices
Si
GaAs
GaP
2H-GaN
AIN
3C-SiC
4H-SiC
6H-SiC
Diamond
Band gap at
300K(eV)
1.12
1.43
2.26
3.44
6.28
2.36
3.26
3.1
5.45
Relative
dielectric
constant
11.8
12.8
11.1
9.5
8.5
9.6
10.3
10.3
5.5
Breakdown
electric field
( 106 V / cm)
0.3
0.4
1.3
3.3
12
1.2
2.0
2.4
10
Electron
mobility at
300K
2
( cm / V S )
1350
8500
350
900
300
900
720
370
2200
Maximum
operating
temperature
(K)
300
460
873
1240
1100
Melting
temperature
( C )
1415
1238
Sublime
>>1800
Sublime
>>1800
Phase
change
power electronic
devices
Current-driven (current-controlled) devices:
thyristor, GTO, GTR
Voltage-driven (voltage-controlled) devices
(Field-controlled devices):power MOSFET,
IGBT, SIT, SITH, MCT, IGCT
Pulse-triggered devices: thyristor, GTO
61
Symbol of Power semiconductor
Devices
63
power electronic
devices
power electronic
devices
Level-sensitive (Level-triggered) devices:
GTR,power MOSFET, IGBT, SIT, SITH,
MCT, IGCT
Uni-polar devices (Majority carrier devices):
SBD, power MOSFET, SIT
Bipolar devices (Minority carrier devices):
ordinary power diode, thyristor, GTO, GTR,
IGCT, IGBT, SITH, MCT
Composite devices: IGBT, SITH, MCT
62
Comparison of the major types of
devices
64
Comparison of the major types of
devices
LOGO
tranvanhung@iuh.edu.vn
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