Advantage of the LED
(OSRAM)
1
LED Cross-Section View
+
引出效率
p- Window Layer
p- Cladding Layer
i- Active Layer
n- Cladding Layer
n- Substrate
Substrat
(absorbierend
oder
transparent)
內部量子效率
−
~ 0.25 mm
2
電流驅動發光原理
3
Different Kinds of Electric Transition
(a) Absorption
(Photodetector)
E2
E2
hν12
Eg (Bandgap)
E1
E1
(b) Spontaneous
Emission
E2
E2
(LED)
E1
E1
E2
E2
E1
E1
(c) Stimulated
Emission
(Laser Diode)
hν12
(Before)
hν12
hν12
hν12
(After)
4
LED發光光譜及其採用材料
White
(OSRAM)
W = White (GaN)
Green
(x=0.32/y=0.31)
Yellow
W = White (InGaN) (x=0.32/y=0.31)
G = Green (GaP:N)
570nm
P = Pure Green (GaP)
560nm
Y = Yellow (AlGaInP)
Colour triangle
0.9
T = True Green (InGaN)
Orange
s
0.8
587nm
O = Orange (AlGaInP)
605nm
525nm
0.7
V = Verde-Green (InGaN) 505nm
Amber
green
0.6
yellow
0.,5
A = Amber (AlGaInP)
615nm
0.4
Blue
B = Blue (InGaN)
0.3
470nm
white
0.2
red
Red
blue
S = Super-Red (AlGaInP) 630nm
0.1
B = Blue (GaN)
466nm
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
H = Hyper-Red (AlGaAs) 645nm
5
AlGaInP及InGaN LED
20 mA
1000
AlGaInP
500
500
on Sapphire
on SiC
on GaAs
200
200
Traditional
100
100
InGaN
AlGaAs
50
20
GaP
Blue
460
Verde
480
500
Green
520
540
Yellow
560
580
Emission Wavelength
50
GaAsP
Orange
600
620
Superred Hyperred
640
Luminous Flux @ 20mA
Luminous Flux @ 20mA
1000
20
660 [nm]
(OSRAM)
6
單晶磊晶層的成長(AlGaInP)
(E. F. Schubert, “Light-Emitting Diode”)
7
Bandgap Energy Eg (eV)
單晶磊晶層的成長(AlGaInN)
Lattice Constant a0 (Å)
8
有機金屬氣相磊晶(MOVPE)設備
(AXITRON)
9
The Planetary Reactor
wafer handler
4” wafer on
rotating satellite
main susceptor
disk
collector ring
(molybdenum)
(AXITRON)
10
質流控制器(MFC)
(M. Quirk and J. Serda, “Semiconductor
Manufacturing Technology”)
11
LED Chips or Dies
12
LED Measurement (Probe Station)
13
LED發光特性的改善
封裝製程
磊晶製程
晶粒製程
LED-Package
LED-Epitaxy
LED-Process
14
p-Contact
2-50 µm p-GaP
Window Layer
0.5-1 µm AlInP Mg-doped
0.5-1 µm AlGaInP Undoped
1.0 µm AlInP Si-doped
n-GaAs Substrate
n-Contact
Normalized Current Density, J(x)
Current Spreading Layer
1.0
P-GaP Current Spreading Window
(a) 2 µm
(b) 15 µm
(c) 50 µm
(c)
0.5 Top Contact
(b)
(a)
0
0
25
50
75
100
125
Distance from Center of Chip, x(µm)
15
Current Spreading Layer
Without
a spreading layer
With
a spreading layer
(E. F. Schubert, “Light-Emitting Diode”)
16
Wafer Bonding
p-Contact
p-GaP Window
(~50µm)
AlGaInP (~2 µm)
Wafer Bonded
n-GaP (~200 µm)
(LumiLEDs)
n-Contact
GaP Epilayer
LED Structure
GaP Epilayer
LED Structure
GaAs Substrate
GaP Epilayer
LED Structure
GaP Epilayer
LED Structure
GaP Substrate
GaP Substrate
GaAs Substrate
(Temperature and Force)
17
Extraction Efficiency
(E. F. Schubert, “Light-Emitting Diode”)
18
Surface Roughening
(Fujii et al., APL, v84, p855, 2004)
Before
etching
After
etching
19
AlInGaP Chip Efficiency Improvement
Batwing
(LumiLEDs)
~ 3x
~ 18x
~ 30x
20
Effect of Epoxy
(ηair )
(E. F. Schubert, “Light-Emitting Diode”)
(η
epoxy
)
21
Different Kinds of LED Packages
(http://en.wikipedia.org/wiki/LED)
(LED Lamps)
(SMT LEDs)
(LED Displays)
(SunLED)
(PCB LEDs)
22
銲線(Ball Bond)
銲線完成照片
(CREE)
23
Flip-Chip InGaN LED
(Nichia)
Transparent
contact layer
P-Contact
P-GaN
Conventional
InGaN LED
MQW
N-Contact
N-GaN
Buffer layer
Sapphire
Sapphire
Buffer layer
N-GaN
MQW
P-GaN
N-Metal
Flip-Chip
InGaN LED
P-Metal
Solder
Submount
(LumiLEDs)
24
Packaging Technology (Power Improvement)
(LumiLEDs)
(Low Power LED)
(High Power LED)
25
RGB LEDs (2)
Diffusion cap
26
Blue LED + Yellow Phosphor (1)
演色性評價指數: ~ 80
色溫: 5000 K.. 6500 K
藍光Blue LED + 螢光粉phosphor
= 白光white LED
(OSRAM)
27
Blue LED + Yellow Phosphor (2)
28
Street and Roadway
(LumiLEDs)
29
Product Design (LED Curing System)
(Innovation in Optics)
Heat Sink
30
Traffic Signals
Sun
Phantom
Prevention
15W
(LumiLeds high power LED *12)
150W
31
Media Boards
~ 1000 m2 LEDs
= 19 mil. LEDs
Times Square, New York
(Thomas Swan)
32
Road Lighting
Very bright and can be seen from up to 4 miles away
(Sweden)
33
Elevated Taxiway LED
(Dialight)
34
LED Automotive Lighting
Lexus
Interior Lighting
Ford Tonka F-350
500 lm*2 for low-beam operation with
side parking lights
Mercedes Benz
128 LEDs in two different colors
18 in each mirror (Amber)
32 in every stop light
28 high mount stop light
35
Forward Lighting
(LumiLEDs)
36
Flashlights and Lighting for Diving
(Fa&Mi)
37
Backlighting Source
(LumiLEDs)
For all types of displays: LCD Televisions, LCD monitors on
laptop computers, and various custom sized LCD displays.
38
Wide Area Lighting
(LumiLEDs)
39
Residential Lighting Application
(LumiLEDs)
40
Capsule Endoscopy
41