Electronic Devices Optoelectronics

8/10/2019 Electronic Devices Optoelectronics

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OPTOELECTRONIC DEVICES


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Light Emitting

Diodes

Red LED White LED

LED for displays Blue LED LED for traffic light

LEDs


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OPTOELECTRONIC DEVICES


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DIODE LASERS

Diode lasers have been used for cutting,

surgery, communication (optical fibre),

CD writing and reading etc
http://www.semiconductor-technology.com/projects/iqe/index.htmlhttp://photos4.flickr.com/6933867_7223c5b695.jpg


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Producing Laser in the

Lab


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Optoelectronic devices for

Photovoltaic Applications


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Solar Cells


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Fibre optics Communication

Transmitter Channel Receiver

IR - Lasers

IR-Photodetector


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Head Mounted Display Applications: Next

generation head mounted display and virtualreality training


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n

nthnppn

/

/

pgand,npassumptionwith the

ln

1

1

th

op

oc

op

kTqV

p

n

nn

p

p

op

kTqV

th

opnpopop

g

g

q

kTV

IenL

pL

qAI

IeII

gLLqAgI


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SOLAR CELLS


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SOLAR CELLS


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Finished Solar Cell Cross Section

SOLAR CELLS


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SOLAR CELLS

ocsc

ocsc

mm

VI.max

VI

VIfactorFill

ffP


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PHOTO DETECTORS

Quantum efficiency ,

Q=(Jop/q)/(Pop/h)

where Jopphotocurrent densityPop- incident optical power density

GAIN BANDWIDTH AND SIGNAL TO NOISE RATIO OF


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GAIN, BANDWIDTH AND SIGNAL-TO-NOISE RATIO OF

AVALANCHE PHOTO DETECTORS


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Signalto-noise Ratio

Johnson NoiseRandom thermal motion of the

carrier

Shot Noiserandom thermal generation-

recombination of EHP

Noise equivalent power (NEP)- is the minimum

detectable signal that would produce the same rms

output as the noise

DetectivityD=1/NEP


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WAVEGUIDE PHOTO DETECTORS


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LIGHT EMITTING MATERIALS


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LIGHT EMITTING MATERIALS


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FIBER OPTIC COMMUNICATION


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Light Amplification by Stimulated Emission of Radiation (LASERS)

kThkTEE een

n //)(

1

2 1212


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B12n1(12) = A21n2 +

B21n2(12)

Absorption = Spontaneous +


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B12n1(12) = A21n2 +

B21n2(12)

Absorption = Spontaneous +Stimulated

emission emission)(

)(

rateemissionsSpontaneou

rateemissionStimulated12

21

21

221

12221

A

B

nA

nB

1

2

21

21

12121

12221

)(

)(

rateAbsorption

rateemissionStimulated

n

n

A

B

nB

nB


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materiallasertheofindexrefractiveisnwhere

2

0 n

mL


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SEMICONDUCTOR LASERS

Population Inversion at a junction

kTFE

i

kTEF

v

kTEF

i

kTFE

c

pivp

innc

eneNp

eneNn

/)(/)(

/)(/)(


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gpn

pn

EFF

hFF

)(

)(


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Emission Spectra for p-n junction Lasers


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m

d

dn

nLn

or

d

dnLLn

d

dm

Lnmor

n

mL

o

ooo

oooo

o

o

12

2

1

2

22

2

2

If we let m=-1, we can calculate the change in

wavelength o between adjacent modes


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Heterojunction Lasers

Basic Semiconductor Lasers


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Double Heterojunction Laser structure


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Double -Heterojunction Laser structure

Separate Confinement and Graded Index Channels


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Separate Confinement and Graded Index Channels

Vertical Cavity Surface Emitting Lasers (VCSELs)


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Vertical Cavity Surface-Emitting Lasers (VCSELs)


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High Frequency and

High-Power Devices


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Tunnel Diode

IMPATT Diode

P-N-P-N Diode

Insulated Gate Bipolar Transistor(IGBT)


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Tunnel Diode

Degenerate n-type if n>NC

Degenerate p-type if p>Nc

Tunnel Diode


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Tunnel Diode

Tunnel Diode Band Diagram


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Tunnel Diode Band Diagram

Tunnel Diode Characteristics


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Tunnel Diode Characteristics

Impact Avalanche Transit-Time (IMPATT) Diode


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Impact Avalanche Transit Time (IMPATT) Diode

Time dependence of the growth and drift of holes in Read Diode


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Time dependence of the growth and drift of holes in Read Diode

Lfv

L

d 2

vfor

1

2

1 d


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The transferred electron mechanism


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e t a s e ed e ect o ec a s

Formation and drift Space Charge Domains


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p g

The P-N-P-N Diode


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Two Transistor Analogy of SCR


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gy

)(1ior

)i(

But

21

21

2121

21

1222

2111

COCO

COCO

CC

BCOC

BCOC

II

iII

iii

iIiiiIii

Forward Blocking State


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g

The Semiconductor Controlled Rectifier (SCR)


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( )

Application of SCR


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pp

Insulated Gate Bipolar Transistor (IGBT)


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p

COMFET- Conductivity Modulated FETIGTInsulated Gate Transistor

IGR- Insulated Gate Rectifier

GEMFET- Gain Enhanced MOSFET

BiFET- Bipolar FET


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Characteristics of IGBT:

It has very high input impedance like MOSFET

It has a low input capacitance

In the ON state , it has low resistance and high

current handling capability

It can turn off more easily than SCR

Electronic Devices Optoelectronics

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