LEDs Basics: LED Fundamentals

LED Basics

LED 101
September 1st, 2010

III/V-Technologies for Optoelectronics
6,2
4,0 AlN
InGaAlP
dgap Energ [eV]

3,5 GaN

m]
gy

Wavelength [nm
400
3,0
SiC
AlP
2,5 500
Band

GaP
2,0 600
InN 700
1,5
15
InGaN GaAs InP

1,0
2,5
25 3,0
30 3,5
35 4,0
40 4,5
45 5,0
50 5,5
55 6,0
60 6,5
65
Lattice Parameter [A]
LED 101 | 09/01/2010 | Page 2
LED Basics | Date: 09/01/2010 | OS SJ AE | RS

How Does a LED Emit Light?
LED Chip Structure
n-Crystal
y p-Crystal
p-contact

-
Anode
P-doped
n-doped
Active
epitaxy
+
layer
l
Substrate Depletion zone

Cathode
Electrons
n-contact Holes
H l

LED 101 | 09/01/2010 | Page 3

Efficiency of an LED

contact
shadowing
h d i
extraction
total internal
Radiative reflection
recombination

Non-radiative
recombinatior

absorption

Internal Efficiency: 60-90% Extraction Efficiency: 50-75%

LED 101 | 09/01/2010 | Page 4

Thinfilm Class - Chip Technology Comparison
Standard Power LED
Thinfilm Technology gy
(generic)
surface emitter
volume emitter
top and bottom contacts
top or bottom contacts

~ 49 % > 97 %
top emission
p
Side emission

 OSRAM O t ’ Thi fil t h l
Opto’s Thin-film technology was th fi t on th market
the first the k t

LED 101 | 09/01/2010 | Page 5

ThinGAN® Scalable Technology Platform
Light Output with Scaleable 5
Chip Size
5
4
Relative Ligh Output

3 2
ht

2
3
1
1 Constant Amp/ mm²
R

4

Emitting Area
Optimize cost and “Usable Lumens”
p
with proper LED Selection
LED 101 | 09/01/2010 | Page 6

Production of a LED and Efficiencies
Conduction Band

Photons

Chip Processing Packaging
Valence Band Light extraction
“Bandgap Engineering” Thermal
Light extraction management
Epitaxy
Electrical losses -conversion
Internal quantum
efficacy

Substrate Wall plug = int . electr . extr . package
.

LED 101 | 09/01/2010 | Page 7

Structure of the LED
LED-Chip
Wire Bond

Epoxy
Lead frame
Lead Bond
Frame Chip Wire
Reflector

Cavity Mold
0.25 mm

Printed Circuit Board (PCB)

1.0 ~ 4.0 mm

LED 101 | 09/01/2010 | Page 8

Structure of the High Power LED

GOLDEN DRAGON PLUS

LED 101 | 09/01/2010 | Page 9

Overview of Packages – T
O i fP k Targeted for Applications
t d f A li ti
Advanced Power OSTAR® OSTAR®
High-Power LED Packages TOPLED® Golden Diamond
Compact SMT
DRAGON® DRAGON®
Plus
Power TOPLED®
Power with lens OSLON SSL® 3.65 x 4.0 x 4.68 x 5.75 x
11.0 x 6.0 1.195 mm 1.1 mm
TOPLED® 3.4 x 3.3 x
x 4.2 mm
1.9 mm
11.0 x 6.0 x
MultiLED® 3.1 mm
3.5 x 2.8 x 3.1 x 3.1 x
TOPLED®
3.6 mm 2.2 mm
3.5 x 2.8 x
1.9 mm
3.4 3.3
34x33x
1.9 mm Dimensions: length x width x height
3.5 x 2.8 x
1.9 mm
SIDELED®
PointLED®
Mini
TOPLED® Micro
Chipled SIDELED®
1.0 SmartLED®
4.0 x 4.0 x
3.4 x 2.5 x FIREFLY ® SmartLED®
3.6 mm
0.725 mm 2.2 x 1.4 x
1.3
1 3 mm 1.6 0.8
16x08x 3.0 x 1.2 x
0.6 mm 1.7 x 0.8 x 1.8 x 1.2 x 1.7 x 0.8 x
Miniature LED Packages 1.0 mm
0.5 mm 0.35 mm
0.6 mm
LED 101 | 09/01/2010 | Page 10

LED Parameters

Optical Quantities
p Electrical Quantities
 Luminous Intensity IV mcd  Forward Voltage VF Volts (min/typ/max)
 Luminous Flux V lm  Forward Current IF Amperes (max/typ)
 Luminance LV cd/m² (nits)  Reverse Current IR
 Beam angle φ
 Dominant Wavelength dom nm
 Color Coordinates Cx, Cy

Thermal Quantities Misc
 Junction Temperature ˚C  Lifetime h
 Temperature Coefficients lm/K, V/K  CRI
 Thermal Resistance K/W  CCT K
 Luminous Efficacy lm/W

LED 101 | 09/01/2010 | Page 11

Spectral Power Distribution of Single-Color LED
S t lP Di t ib ti f Si l C l LEDs

A single-color LED emits light in a narrow spectral band,
resulting in a saturated color.

1,0
GaN blue (465)
( )
relative intensity of the LED radiation
n

0,9
09 InGaN blue (470)
0,8 verde (505)
true green (525)
0,7 pure green (560)
0,6
06
green (570)
e

yellow (587)
ll
0,5 orange (605)
amber (617)
0,4 super-red (632)
0,3 hyper-red (645)
e

0,2
0,1
0,0
380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760
wavelength [nm]

LED 101 | 09/01/2010 | Page 12

LED M i l and C l
Materials d Colors
White
W = White (GaN) (x=0.32/y=0.31)

W = White (InGaN) (x=0.32/y=0.31)

Green Yellow
Y = Yellow (InGaAlP) 587nm
V= Verde-Green (InGaN) 505nm

T= True Green (InGaN) 525nm
Orange
O = Orange (InGaAlP) 605nm
P=Pure Green (InGaAlP) 560nm

G= Green (InGaAlP) 570nm Amber (Orange Red)
A = Org. Red (InGaAlP) 617nm

Blue
B = Blue (InGaN) 470nm
Red
S = Super-Red (InGaAlP) 630nm
B = Blue (GaN) 466nm

H = Hyper-Red (GaAlAs) 645nm
D = Deep Blue (InGaN) 455nm

LED 101 | 09/01/2010 | Page 13

How Does LED Generate White Light?

White LED Approaches
Tri-Color Colorimetry
RGB-
Red/ Green/ Blue – primary colors Chips + +
400 500 600 700nm
White
Whit – mixture of 3 primary colors
i t f i l
Blue + Yellow
Chip Chip
400 500 600 700nm

Blue 1 Phosphor
Chip +
400 500 600 700nm

UV-
3 Phosphors
Chip + +
White = Red + Green + Blue 400
Emission Wavelength
500 600 700nm

LED 101 | 09/01/2010 | Page 14

White light from LEDs
Blue InGaN chip + Phosphor = White LED

Blue Chip Yellow Phosphor

InGaN LED Single-Chip White, LW W5AM
ctral Power (%)
(

YAG Phosphor
Relative Spec

White LED
R

Wavelength (nm)

Wavelength (nm)

LED 101 | 09/01/2010 | Page 15

Volume / Chiplevel Conversion (CLC)
Yellow Blue
Volume conversion
Converter particles
dispersed in casting /
molding material

Chiplevel Conversion (CLC)
Phosphor layer on surface
emitting chip Yellow Blue

LED 101 | 09/01/2010 | Page 16

Phosphor Technology

Customer-selected LED color
t e es a e poss b e
themes are possible
New color regions
capable with Color on Demand

LED technology
Epoxy with
Phosphor

Blue LED Chip

LED 101 | 09/01/2010 | Page 17

Correlated Color Temperature (CCT)
C l t dC l T t
Color Temperature Chart
Correlated Color Temperature (CCT) 7000K
Defines a color as the temperature [K] that a
"black body" source must reach in order to Standard white LED
produce that same color. 6,500 K
6000K

5000K Noon sunlight

Cold Fluorescent
4,200 K
4000K
Std. Metal Halide
4,000
4 000 K
Halogen
3000K 3,000 K

Std. Incandescent
2,850 K
2000K
LED 101 | 09/01/2010 | Page 18

Spectrum of Whit LED in Various Color Bins
S t f White i V i C l Bi
1 7139K
5L-7139K
0.9
6819K
6L-6819K
6L 6819K
5423K
7L-5423K
0.8
4831K
8L-4831K
0.7
07 3945K
J4-3945K
Relative Radiant Power

0.6
3374K
M4-3374K
2833K
Q4-2833K
0.5
R

0.4

0.3

0.2
02

0.1

0
380 400
00 420
20 440
0 460
60 480
80 500
00 520
20 540
0 560
60 580
80 600 620 640
6 0 660 680 700
00 720
20 740
0 760
60 780
80
Wavelength (nm)

LED 101 | 09/01/2010 | Page 19

Color Rendering Index (CRI)

 Color Rendering Index (CRI) – is a quantitative measure of the ability of a
light source to reproduce the colors of various objects faithfully in comparison
with an ideal or natural reference light source with the same CCT

Reference Li ht Source:
R f Light S
 For CCT<5000K, Planckian radiator of
that CCT;
 For CCT>5000K, mathematically
derived daylight t th
d i d d li ht at the nearest CCT
t

Color Samples: 8 Standard Color Samples
 8 standard color samples for
calculating CRI values
l l ti l
 6 special color samples for evaluating
saturated color rendering, skin tone
and green foliage Special Color Samples #9 to #14

LED 101 | 09/01/2010 | Page 20

Disclaimer

 All information contained in this document has been checked with the greatest care.
OSRAM Opto Semiconductors GmbH can however, not be made liable for any damage
that occurs in connection with the use of these contents
contents.

 OSRAM Opto Semiconductor GmbH makes no representations and warranties as to a
possible interference with third parties' intellectual property rights in view of products
originating from one of OSRAM Opto Semiconductor GmbH's partners, or in view of
products being a combination of an OSRAM Opto Semiconductor GmbH's product and
a product of one of OSRAM Opto Semiconductor GmbH's partners. Furthermore,
OSRAM Opto Semiconductors GmbH cannot be made liable for any damage that
occurs in connection with the use of a product of one of OSRAM Opto Semiconductor
GmbH's partners, or with the use of a combination of an OSRAM Opto Semiconductor
GmbH's product and a product of one of OSRAM Opto Semiconductor GmbH's
partners.

LED 101 | 09/01/2010 | Page 21

LEDs Basics: LED Fundamentals

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LEDs Basics: LED Fundamentals