English ability would save life

1
Why English is Important

• English ability would save life
• English ability gives you opportunities
• http//www.youtube.com/watch?vtcseWVN
  mda8
• e.g. Job opening in TSMC
• http//www.tsmc.com/chinese/careers/jo
  bs.html

http//www.youtube.com/watch?vGT86iWiH2mI
2
What should you do to learn English in this class?

• Read largely
• - preview textbook before class
• - review textbook and note after class
• Increase your vocabulary
• Invest your time to learn English regularly
• - Reading
• CNN, yahoo, newspaper
• - Listening
• radio
• youtube
• watching TV

3
Ch.1 Introduction

• Optoelectronic devices
• - devices deal with interaction of electronic
  and optical processes
• Solid-state physics
• - study of solids, through methods such as
  quantum mechanics, crystallography,
  electromagnetism and metallurgy
• Elemental semiconductors
• - Si, Ge, ..etc.
• - indirect bandgap, low electric-optics
  conversion efficiency
• Compound semiconductors
• - III-V (e.g. GaN, GaAs), II-VI
• - direct bandgap, high electric-optics
  conversion efficiency
• GaAs, InP
• - higher mobility than Si, Ge,
• - energy band gap, Eg 1.43 (GaAs), 1.35 (InP)
• - most common substrate, used to grow up
  compound semiconductors

4
Periodic Table
5
Band structure

• Band structure
• - results of crystal potential that originates
  from equilibrium arrangement of atoms
• in lattice
• - directed from potential model and electron
  wave equation (Schrodinger equation)
• time-dependent Schrodinger equation
• E electron energy, fwave equation, m
  electron mass, h Plank constant

6
Electron energy band diagram v.s. wave number
7
Energy bandgap v.s. lattice constant
8
Wavelength (Bandgap) Engineering
 
Reference article http//www.tf.uni-kiel.de/matwi
s/amat/semi_en/kap_5/backbone/r5_1_4.html
9
Energy bandgap v.s. lattice constant

• Constrains for forming compound semiconductors
• (1) requirement of lattice match, (2)
  availability of suitable substrates
• GaAs and InP are most common substrates used to
  grow up compound semiconductors
• (Note InAs, InSb and GaSb substrates are
  availabe, but not as readily as GaAs and InP,
• moreover, all the ternary and quaternary
  alloys of interest are mis-matched to these
  substrates)
• only InxGa1-xAs and InxAl1-xAs lattice-matched
  on InP substrate
• all AlxGa1-xAs can lattice-match on GaAs
  substrate

10
 
11
Bonding in solids

• Van der Waals bonding
• attractions between atoms, molecules, and
  surfaces.
• e.g. inert gas (like Ar), the ability of
  gecko to hang on a glass surface
• Ionic bonding
• electron exchange between atoms produces
  positive and negative ions
• which attract each other by Coulomb-type
  interactions
• e.g. NaCl, KCl
• covalent bonding
• sharing of electrons between neighboring atoms
• e.g. elemental and compound semiconductors
• Metallic bonding
• valence electrons are shared by many atoms
  (bonding not directional, electron
• free or nearly free contributed to
  conductivity)
• e.g. Zn

12
Body-Centered Cubic (BCC) structure

http//stokes.byu.edu/bcc.htm
e.g. iron, chromium, tungsten, niobium
13
Face-Centered Cubic (FCC) structure
e.g. aluminum, copper, gold, silver

http//stokes.byu.edu/fcc.htm
14
Diamond Cubic (FCC) structure

http//zh.wikipedia.org/zh-tw/FileDiamond_Cubic-F
_lattice_animation.gif
15
Diamond structure v.s. Zincblende structure

• Diamond structure,
  Zincblende structure

e.g. GaAs, and some many binary
compound semiconductors
e.g. Si, Ge
16
Atomic arrangement in different solids
17
Dislocation strain

• Dislocation occurs if
• - epitaxial layer thickness gt hc (critical
  thickness), or
• - epitaxial layer thickness lt hc, but with
  large mismatch
• Strain occurs if
• - epitaxial layer thickness lt hc , and with
  small mismatch

18
Strain semiconductor

• a) lattice match
• b) compressive strain
• c) tensile strain
• Strain offers flexibility for restriction of
  lattice mismatch
• Pseudomorphic thin film take on morphology
  (lattice
• constant) of the substrate

19
Crystal Growth

• Bulk growth
• - furnace growth
• - pulling technique
• e.g. Czochralski
• Epitaxial growth
• - Liquid Phase Epitaxy (LPE)
• - Vapor Phase Epitaxy (VPE), or termed Chemical
  Vapor Deposition (CVD)

20
Epitaxy

• epi means above
• taxis means in order manner
• epitaxy can be translated to to arrange upon
• with controlled thickness and doping
• subtract acts as a seed crystal, deposited film
  takes on a lattice structure and
• orientation identical to the subtract
• different from thin film deposition that deposit
  polycrystalline or amorphous film
• - homoepitaxy epi and subtract are with the
  same material
• epi layer more pure
  than subtract and have different doping level
• - hetroepitaxy epi and subtract are with
  different material
• Examples includes
• - Si-based process for BJT and CMOS, or
• - compound semiconductors, such as GaAs

21
Epitaxy Material Growth Methods

• Liquid Phase Epitaxy
• Vapor Phase Epitaxy (VPE), or termed Chemical
  Vapor Deposition (CVD)
• - formation of condensed phase from gas of
  different chemical composition
• - distinct from physical vapor deposition (PVD)
  such as sputtering, e-beam
• deposition, MBE (condensation occurs without
  chemical change)
• - gas stream through a reactor and interact on
  a heated subtract to grow
• epi layer
• Molecular Beam Epitaxy

22
Doping of Compound Semiconductors

• Intrinsic materials undoped
• - Undoped materials by epitaxy technology have
  more carriers than in intrinsic
• material. e.g. GaAs 1013 /cm3
  (instrinsic carrier concentration 1.8x106 /cm3)
• - impurity comes from source materials,
  carrier gases, process equipment, or
• subtract handle
• Extrinsic materials
• - n-type III sub-lattice of III-V compound is
  substituted by IV elements
• impurity terms donor
• - p-type V sub-lattice of III-V compound is
  substituted by IV elements
• impurity terms acceptor

http//www.siliconfareast.com/sigegaas.htm
23
Optical fiber

• Silica optical fibers have a lowest loss at 1.55
  um, and a lowest dispersion at 1.3 um
• In0.53Ga0.47As (Eg0.47ev)/In0.52Al0.48As
  (Eg1.45ev) heterojunction on InP can be used for
  optical fiber because Eg of InGaAs is close to
  1.55 and 1.3 um
• Note Why GaAs/AlGaAs cant be used here?

24
Energy band theory