Post on 09-Apr-2018
transcript
8/8/2019 Introduction to Op to Electronics
1/25
1
Introduction toOptoelectronic Devices
Jing Bai
ECE Assistant Professor
Office: MWAH 255Tel: (218)726-8606
Email: jingbai@d.umn.edu
8/8/2019 Introduction to Op to Electronics
2/25
2
Outline
What is the optoelectronics?
Major optoelectronic devices
Current trend on optoelectronic
devices
My current research work on
nanoscale optoelectronic devices
8/8/2019 Introduction to Op to Electronics
3/25
3
What Did the Word Opto-
Electronics Mean?
Optoelectronics is the study and application of
electronic devices that interact with light
Electronics
(electrons)
Optics
(light or photons)
Optoelectronics
8/8/2019 Introduction to Op to Electronics
4/25
4
Examples of Optoelectronic Devices
8/8/2019 Introduction to Op to Electronics
5/25
5
Major Optoelectronic Devices
Direct Conversion Between Electrons and Photons
Light-emitting diodes (LEDs)
(display, lighting,)
Laser diodes (LDs)
(data storage, telecommunication, )
Photodiodes (PDs)
(telecommunication, )
Solar Cells
(energy conversion)
8/8/2019 Introduction to Op to Electronics
6/25
6
Light-Emitting Diodes (LEDs)
Light-emitting diode (LED)is asemiconductor diode that emits
incoherent narrow-spectrum light
when electrically biased in the
forward direction of the p-n junction.
8/8/2019 Introduction to Op to Electronics
7/25
7
Photon Emission in Semiconductor
EF
EC
EV
Conduction
band
Valenceband
Photon
Eg
When an electron meets a
hole, it falls into a lower
energy level, and releases
energy in the form of a
photon.
The wavelength of the light
depends on the band gap
of the semiconductormaterial
Semiconductor materials: Si, Ge, GaAs, InGaAs, AlGaAs, InP, SiGe, etc
8/8/2019 Introduction to Op to Electronics
8/25
8
Operation Principle of LED
8/8/2019 Introduction to Op to Electronics
9/25
9
Semiconductor Materials vs.
LED ColorGeneral Brightness
GaP GaN GaAs GaAIAs --
Green, Red Blue Red, Infrared Red, Infrared --
Super Brightness
GaAIAs GaAsP GaN InGaN GaP
Red Red,Yellow Blue Green Green
Ultra Brightness
GaAIAs InGaAIP GaN InGaN --
Red Red,Yellow, Orange Blue Green --
8/8/2019 Introduction to Op to Electronics
10/25
10
Application of LEDs
Display
Solid-state lighting
Communication
Remote control, etc
LED lights on an Audi S6
8/8/2019 Introduction to Op to Electronics
11/25
11
Laser Diodes (LDs)
Lasers (Light Amplification by Stimulated Emission)
Photon emission processes:
Absorption
Photodetectors
Spontaneous emission
LEDsStimulated emission
Lasers
8/8/2019 Introduction to Op to Electronics
12/25
12
Laser Cavity Design
8/8/2019 Introduction to Op to Electronics
13/25
13
Photo Diodes (PDs)
A photodiode is a semiconductor diode that functions as aphotodetector. It is a p-n junction or p-i-n structure. When a
photon of sufficient energy strikes the diode, it excites an
electron thereby creating a mobile electron and a positively
charged electron hole
8/8/2019 Introduction to Op to Electronics
14/25
14
Operation Principle of a PD
8/8/2019 Introduction to Op to Electronics
15/25
15
PDs Detection Range and Materials
Material Wavelength range (nm)
Silicon (Si) 1901100
Germanium (Ge) 4001700
Indium gallium arsenide(InGaAs)
Lead sulfide (PbS)
8002600
8/8/2019 Introduction to Op to Electronics
16/25
16
Solar Energy Spectrum
Spectrum of the solar energy
Solar radiation outside
the earths surface:
1.35 kW/m2, 6500 times
larger than worldsenergy demand
AM0: radiation above the earths atmosphere
AM1.5: radiation at the earths surface
Blackbody radiation: ideal radiation
8/8/2019 Introduction to Op to Electronics
17/25
17
Vision of Solar Cells (Photovoltaics)
Solar Energy Free
Essentially Unlimited
Not Localized
Solar Cells
Direct Conversion of Sunlight Electricity No Pollution
No Release of Greenhouse-effect Gases
No Waste or Heat Disposal Problems
No Noise Pollution very few or nomoving parts
No transmission losses on-SiteInstallation
Why solar cells?
8/8/2019 Introduction to Op to Electronics
18/25
18
Operation Principle of Solar Cells
8/8/2019 Introduction to Op to Electronics
19/25
19
Residential and Commercial Applications
Challenges:
cost reduction via: a) economy of scales b) building integration and
c) high efficiency cells
8/8/2019 Introduction to Op to Electronics
20/25
20
Trends in optoelectronic devices
Long wavelength, high power light sources or
photodetectors
Nanoscale devices Low cost, easy fabricated materials
High opto-electronic conversion efficiency
Multi-wavelength sources
Next, my current research topic
nanoscale optoelectronic devices
8/8/2019 Introduction to Op to Electronics
21/25
21
Quantum Cascade Lasers MIR Light Emission
50.0
UV (FIR)VIS NIR
40.0
30.0
20.0
10.03
.0
2.0
1.5
0.7
0.3
0.4
0.5
0.6
WaveLe
ng
th(
m)
MIR (3~30 m)
Part of the SpectrumSun
The wavelength of quantum cascades laser lies in
the mid-Infrared (MIR) region (3~30 m)
Many chemical gases have strong absorption in
mid-infrared region, such as CO,NH3,
, NO, SO2,
, etc.
8/8/2019 Introduction to Op to Electronics
22/25
22
Quantum Cascade Lasers (QCLs)
a New Light Generation Mechanism
Quantum well laser
Interband transition
QCL Intersubband
transitionCascading effect
Advantages:
Wavelength depends on layer thickness (flexible design)
Well-mastered materials can be used for long wavelength
Multiple colorscan begenerated in same laser
High output power due to cascading effect
8/8/2019 Introduction to Op to Electronics
23/25
23
Applications of QCL
Environmental sensing and pollution monitoring
Industrial process control
Automotive
Combustion control, catalytic converter diagnostics
Collision avoidance radar, cruise control
Medical applications
Breath analysis; early detection of ulcers, colon cancer, etc.
Military and law enforcement
QCL for gas detection
8/8/2019 Introduction to Op to Electronics
24/25
24
Quantum Dot Superlattice Solar Cell
Au grid bar
p+ GaAs substrate
100 nm p GaAs
100 nm n GaAs
30 nm n GaInP
200 nm n+ GaAs
Aucontact
Si: GaAs
Si: GaAs
Si: GaAsSi: GaAs0.5 m intrinsic
region containing
50 layers of
quantum dot layers
8/8/2019 Introduction to Op to Electronics
25/25
25
Quantum Dot Superlattice Solar Cell
ECV
CB
VB
IB
ECI
EIVh(
1+
2)
orh3
Current-voltage relationship
Band structure of quantum
dot superlattices