Section 1
ECE162C, Professor Blumenthal
Section 1, Slide 1
Course Info
Catalog Description:
Electrical and optical properties of semiconductor materials. Direct and indirect gap
semiconductors. Luminescence. Bulk and quantum well materials. Fundamentals of
optoelectronic devices. LEDs. Photoconductors. Photodiodes. Modulators. Integrated
optics and lasers.
Course Prerequisites:
ECE 162A, 162B
Required Text: OPTOELECTRONICS AND PHOTONICS: PRINCIPLES AND
PRACTICES by Kasap (4th Edition), Course Notes
Recommended Reading:
Optical Electronics in Modern Communications, A. Yariv, ISBN 0-19-510626-1, 6th
Edition, Oxford University Press, 2006.
Electrical Properties of Materials, L. Solymar and D. Walsh, 7th Edition, Oxford Press
ECE162C, Professor Blumenthal
Section 1, Slide 2
Course Topics
1.
2.
Review of wave propagation in dielectrics and gain media. Waveguide basics.
Electronic properties of semiconductor materials for optoelectronic devices:
Develop firm understanding of the theory and fundamental electrical characteristics of semiconductor
materials relevant to optoelectronic devices.
3.
Optical properties of selected semiconductor materials:
Develop sound understanding of basic optical characteristics of some semiconductor materials.
4.
P-N junction – the basic structure for optoelectronic device realization
Gain sound understanding of the principles of operation of various junctions, including Schottky contacts and
heterojunctions and their importance to optoelectronic device fabrication.
5.
Light Emitting Diodes (LEDs):
Develop good understanding of the principles of operation of LEDs, their structures and applications.
6.
Semiconductor Laser Diodes
Understand the principles of operation of semiconductor laser diodes and the role they play in modern fiber
optic communication systems.
7.
Photodetectors
Understand the operation of different types of photodetectors: PIN, APD, Photoconductive and Bolometer.
8.
Optoelectronic modulators and integrated optics
Understand the principles of the electro-optic effect, materials that exhibit the EO effect and how they can be
fabricated into practical intensity or phase modulators.
Section 1, Slide 3
ECE162C, Professor Blumenthal
Homework and Grading
Homework:
Will be assigned each week and due the following week at the
start of class. Late homework up to 1 day late will receive
20% reduction in grade. Assignments handed in more than 1
day after due date will not be graded.
Grading:
Homework:
Midterm Exam:
Final Exam:
ECE162C, Professor Blumenthal
30%
30%
40%
Section 1, Slide 4
Historical and Projected Fiber Capacity
Winzer PJ, Neilson DT, Chraplyvy AR. Fiber-optic transmission and networking: the previous 20 and the next 20 years [Invited]. Opt
Express. 2018;26(18):24190-239.
ECE162C, Professor Blumenthal
Lecture 1, Slide 5
DCs and Warehouses
Courtesy of Chris Johnson, Google
DCs also come in all sizes.
There are container drop-ship warehouses, etc.
ECE162C, Professor Blumenthal
Section 1, Slide 6
Ethernet Switches: Today’s Drivers of
the Fiber Bandwidth
Today: Barefoot Newport – 12.8T
32 x 400G in 1RU
12.8Tb/s
(2019)
Optics
Switch ASIC
https://barefootnetworks.com
ECE162C, Professor Blumenthal
Section 1, Slide 7
Ethernet Switches and Silicon Photonics
2020- Intel co-packaged switch + silicon photonics optics.
12.8 Tbps Barefoot Tofino-2 + array of 1.6 Tbps silicon photonics
transceivers. How many fibers is that?
ECE162C, Professor Blumenthal
Section 1, Slide 8
Atomic and Quantum Science and Applications
Space-Based, Mobile
Applications, Climate Science
Quantum
New physics
and
discoveries
Biology,
Physical, and
Life Sciences
Fiber Communications
and Distributed
Computing, Quantum
and Precision Fiber
Applications
Test and
Measurement
ECE162C, Professor Blumenthal
Portable Position, Navigation
and Timing, optical atomic
Quantum Computing,
clocks
Communications, and Sensing
Gravitational Sensing
Section 1, Slide 9
Precision, Atomic and Quantum Experiments
Ions for Quantum
Computing
(Quantinuum)
Gravitational Wave
Detection (LIGO)
ECE162C, Professor Blumenthal
Entangled Atoms for Quantum
Sensing (Ye Group, JILA/CU)
Silicon nitride ultra-low loss platform
(Blumenthal group, UCSB)
ATOMIC Clocks (NIST/JILA)
Section 1, Slide 10
Optoelectronics
ØPhotodetectors:
ØUsually crystalline material (lower dark current,
hence better sensitivity)
ØBandgap smaller than required (but no more
than necessary. Smaller bandgaps tend to have
larger dark currents).
ØLasers
ØAlways crystalline material
ØBandgap equal to hc/l
ECE162C, Professor Blumenthal
Section 1, Slide 11
Growth
Ø MBE:
Ø Molecular beam epitaxy
Ø MOCVD:
Ø Metal organic chemical vapor deposition
Ø Substrate:
Ø Binary (otherwise every wafer is a little different)
Ø Epitaxy
Ø Requires lattice constant equal to binary substrate.
Ø Correct lasing wavelength
Ø Requires correct bandgap.
Ø A quaternary layer
Ø Is required (two degrees of freedom): InxGa1-xAsyP1-y
ECE162C, Professor Blumenthal
Section 1, Slide 12
Ternary Materials
Ø Mix two binaries together. The bandgap is
approximately the arithmetic average of the two
(Vegard’s law) e.g. GaxAl1-xAs
Ø There are two types of sites: group III and group V.
(II-VI compounds also possible).
Ø Ternaries cannot be grown on binary substrates in
general because the lattice constants don’t line up
and dislocations occur. Special case: GaxAl1-xAs
because the lattice constants of GaAs and AlAs are
almost equal.
ECE162C, Professor Blumenthal
Section 1, Slide 13
Quaternary materials
Ø To match bandgap and lattice constant, two degrees of
freedom are required.
Ø Example: GaxIn1-xAsyP1-y
Ø X is the fraction of group III sites occupied by Ga.
Ø Y is the fraction of group V sites occupied by As.
Ø In a bandgap chart, the dots are binaries, the lines are
ternaries, and the regions bounded by 4 lines are quaternaries.
ECE162C, Professor Blumenthal
Section 1, Slide 14
In a bandgap chart, the dots are binaries, the lines are ternaries, and the
regions bounded by 4 lines are quaternaries.
ECE162C, Professor Blumenthal
Section 1, Slide 15
ECE162C, Professor Blumenthal
Section 1, Slide 16
Epitaxial Layers
ØEpitaxial layers of different compound
semiconductors can be grown on top of each
other.
ØSmall differences in lattice constants can be
accommodated for thin layers (strained layers:
Compressive or tensile).
ØToo much accumulated strain results in
dislocations.
ECE162C, Professor Blumenthal
Section 1, Slide 17
Bandgap Heaven
• Offsets in blue #s
• Bandgaps in black
• Units are meV
450
1350
InSb
220
AlSb
1550
200
500
450
AlAs
2170
GaSb
770
GaAs
1420
200
InAs
360
InGaAs
760
InGaP
1900
InAlAs
1460
InP
1350
150
DEC [InAs-AlSb] = 1.35eV
m* [InAs] = 0.023 me
250
200
550
170
200
InAs RT µ > 30,000 cm2/Vs
ECE162C, Professor Blumenthal
Section 1, Slide 18