p16-semiconductor photon sources

7/27/2019 P16-Semiconductor Photon Sources

1/33

16. Semiconductor Photon Sources


2/33

Electroluminescence devices

Light-emitting diode Laser diode(LED)

optical amplifier

(SOA)

(LD)


3/33

Evolution of Lighting to LEDs


4/33

LUX (lx)?, LUMEN (lm)?, CANDELA (cd)?

Table 19-1Radiometry and Photometry

radiometry photometry

watt (W) lumen (lm)Radiant flux : : Luminous fluxm

W/srW/(sr.m2)

ux x

candela (cd)Cd/m2

rra ance :

Radiant intensity :Radiance :

: illuminance

: luminous intensity: luminance


5/33

CIE (International Commission on Illumination)

555 nmRadiant f lux

of 1 Watt at 555 nm isthe luminous f lux

of 685 lm (lumen)

Radiant f luxof 1 Watt at 610 nm is

610 nm

Luminous efficiency V()

e um nous ux

of 342.5 lm (lumen)

Photometric uni t

=

Ex) 100 lm/W means,

At Green ~ 100/680 ~ 15 %

At Blue/Red ~ 100/340 ~ 30%

(If QE ~ 100%)


6/33

Semiconductor Light for Visualization

Osram SID 2004


7/33

Semiconductor Light for Illumination

Osram SID 2004


8/33

LED Roadmap for Automotive

Osram SID 2004


9/33

LED characteristics

+

-


10/33

Forward voltage for LEDs


11/33

!-.


12/33

LED characteristics

Internal efficienc

Extraction efficiency

External efficiency

Power-conversion efficiency (or, wall-plug efficiency)

[ ]power ext extP h

for h eVIV eV

= =

Luminous efficienc lm/W

{ } { }/ 685 ( ) 685 ( )lm W ext P hV VIV eV

= =


13/33


0

2

2 s n

2 (1 cos )c

r r

r

=

=

24extract

r

=

2

(1 cos )2

1

c=

2

2

1

1.9 % for 3.6 (GaAs)extract

n =

n

4 % for 2.5 (GaN)n =


14/33



15/33

Spatial pattern of emitted light


16/33


Photonic Crystal-LEDs

BabaLimited by surface recombination

Good scheme!!!

Limited by surface recombination

Good scheme!!!

Lumiled100 um device size achievable.

Several layer of PC for extraction.Good internal quantum efficiency

N d d ( 90%)

100 um device size achievable.Several layer of PC for extraction.Good internal quantum efficiency

N d d ( 90%)eeded (>90%).Multiple pass limits device size (~10um).

Small volume needed.Not so good for lighting

Needed (>90%).Multiple pass limits device size (~10um).

Small volume needed.Not so good for lightingot so good for lighting.

Surface recombination limited

Surface recombination limited.

Not so good for lighting.Surface recombination limited

Surface recombination limited.

Noda


17/33


18/33

OLED (Organic Light Emitting Diode)

OLED (/ ) , .

. ( .) . .

. . (LCD 1,000 ) , . ( LCD ) ( LCD 1/3 ) .


19/33

OLED Structure

100 500 nanometers thick


20/33

Organic LEDs (OLEDs)

Discovered by Ching Tang and Van Slyke at Eastman Kodak in 1987.


21/33

OLED


22/33

But, OLEDs are

Life time blue organics have shorter li fe time compared to red and green

Manufacturing - expensive

Moisture can damage OLED


23/33

Resonant-cavity LEDs (RC-LEDs)

RCLED spectrum


24/33

Semiconductor optical amplifiers (SOA)

forward-biased

heavily doped

p-n junction

If the intraband relaxation time is much shorter than the interband relaxation time,

a steady-state population inversion between the bands may be established.

Optical Pumping Electric-Current Pumping


25/33

Heterostrctures

Injected carrier

concentration Narrower

(Double)Heterostructures

is important

l


26/33

Microcavity lasers

VCSEL


27/33


28/33


29/33

Quantum Cascade Lasers


30/33

QCL


31/33

QCL


32/33

QCL


33/33

QCL

p16-semiconductor photon sources

Documents