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課程講義
光電元件物理
南台科技大學光電系 吳坤憲
1
Physics of Optoelectronic Devices
Part I.
Introduction to Physics of Semiconductor Devices
Part II. Basic Concepts of Optoelectronic Devices
Part III. Light Emitting Diodes (LEDs)
Part IV. Semiconductor Laser Diodes
Part V. Photodetectors and Solar Cells
Part VI. Fabrication Technology
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I. Introduction to Physics of Semiconductor Devices

半導體材料

Solid-State Materials

Semiconductor Materials

Basic Crystal Structure

Energy-band Diagram

Intrinsic and Extrinsic

半導體元件 (Devices)

Junctions

Carrier Transport

The P-N Diode

BJT and MOSFET
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5W for Semiconductors
 What?
 導電度界於導体與絕緣體之間的材料
 Why?
 半導體為現代電子工業的核心
 Where?
 應用於幾乎所有的電子產品(元件)
 When?
 1988年起電子工業成為世界上最大規模的工業
 How?
 導電性可控制
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Solid-State Materials
•
Conductor
– Mn: ~ 105
– Cu: ~ 8 × 106
– Fe: ~ 107
•
Semiconductor
– Si: ~ 105
– doped-Si: 105 ~ 10-5
•
Insulator
– Quartz: ~ 10-18
– Plastics: ~10-13
– GaAs: ~ 10-6
 Resitivity (-cm)
 Conductivity (-cm)-1
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Portion of the Periodic Table related to semiconductors
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Element and Compound Semiconductors
 Element semiconductors
 Si, Ge, C (diamond).. , etc..
 Compound Semiconductors
– III-V compound semiconductors
• Binary: GaAs, InP, GaP, GaN, AlAs,
InAs…
• Ternary: Al1-xGaxAs, GaAsxP1-x , InxGa1-xAs
• Quaternary: InxGa1-xAsyP1-y
– II-VI compound semiconductors
• CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO,
HgCdTe, etc..
– IV-IV compound semiconductors
• SiC, SiGe
– IV-VI compound semiconductors
• PbS, PbTe
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Various Semiconductor Materials
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改變半導體導電性的主要方法
 溫度 (Temperature)
–
Thermal sensors
 照光 (Illumination)
– optoelectronic devices : Photodetector, Solar Cell….ect..
 摻雜 (Doping)
– 大幅增加導電度
– 形成P 型及N型半導體
– 形成P/N接面:多數半導體元件之基本結構
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Applications of Semiconductors Device
表 1-1　主要的半導體材料及相關的應用領域
種　類
材　料
應　用
積體電路 (Integrated Circuits)
Si
Si
太陽能電池 (Solar Cell)
微機械元件 (Micromechanics)
化合物
GaAs
高速、高頻積體電路
GaP
發光二極體 (Light Emitted Diode)
InP
光測器 (Photo Detector)
ZnSe
半導體雷射 (Semiconductor Laser)
ZnS
平面顯示器 (Flat Panel Displays)
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Crystallization of materials
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Crystal and Lattice

Crystal (結晶體)
–


The semiconductor materials are basically assumed as
single crystals to simplify the analysis.
Lattice (晶格)
– The periodic arrengment of atoms in a crystal
Lattice Constant (晶格常數)
– The dimension a is called the lattice constant
Three cubic-crystal unit cells. (a) Simple cubic. (b) Body-centered cubic (c) Face-centered cubic.
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The Diamond Structure
(a) Diamond lattice.
(b) Zincblende lattice.
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Crystal Plane and Direction
A (623)-crystal plane
Miller indices of some important planes in a cubic crystal
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Covalence Bonds
A tetrahedron bond (a) 3-D. (b) 2-D
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Conduction Electron and Hole
Formation of intrinsic carriers
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Donor and Acceptor
Formation of extrinsic carriers
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Energy-Band Diagram
Metal
Semiconductor
Insulator
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Simplified Energy-Band Diagram
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Energy-Momentum Band Diagram
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Band Structures for Si and GaAs
Si
GaAs
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Direct and Indirect Bandgap Semiconductors
•
•
Direct transition: band to band  photon emission
Indirect transition: via defect or impurity-related states  phonon emission
Direct Bandgap
Indirect Bandgap
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Extrinsic (Doped) Semiconductor
Donor Level
Acceptor Level
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Various Impurities
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Intrinsic, N-type and P-type semiconductors
(1) Intrinsic
(2) N-type
(3) P-type
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Intrinsic and Extrinsic Silicon
 Intrinsic Semiconductor (本質半導體)
– 導電電子數量與電洞數量大約相同的半導體
– 通常指未經摻雜的半導體(Undoped Semiconductor)
 N-type Semiconductor (N型半導體)
– 多數載子(majority carrier)為電子的半導體
– 矽晶體中摻雜V 族原子則形成N型半導體
 P-type Semiconductor (P型半導體)
– 多數載子(majority carrier)為電洞的半導體
– 矽晶體中摻雜III族原子則形成P型半導體
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Impurities for III-V Compound Semiconductors
 Donor (施體)
– Column IV (S, Se,Te, etc.) impurity substitute for column V (As)
 Acceptor(受體)
– Column II (Be, Zn, Cd, etc.) impurity substitute for column III (Ga)
 Amphoteric impurity (雙性雜質)
– substituting Ga for donor (low T)
– substituting As for acceptor (high T)
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Basic Building Blocks of Semiconductor Devices
(a) M-S Junction (b) P-N Junction (c) Heterojuction (d) MOS structure
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Semiconductor Devices
•
Bipolar Devices
–
–
–
–
•
Unipolar Devices
–
–
–
–
–
•
P-N Junction Diode
Bipolar Junction Transistor (BJT)
Heterojunction Bipolar Transistor (HBT)
Thyristor and related power devices
Junction Field Effect Transistor (JFET)
Metal-Oxide-Semiconductor FET (MOSFET)
MOS Diode (Capacitor)
Complementary MOS (CMOS)  BiMOS and BiCMOS
Power MOS
High-Speed Devices
–
–
Metal-Semiconductor FET (MESFET)
Modulation-Doped FET (MODFET), High-Electron-Mobility Transistor (HEMT)
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Semiconductor Devices (continued)
•
Microwave Devices
–
–
–
–
–
•
Tunnel diode
IMPATT diode
Transferred-Electron Device (TED)
Quantum-Effect Devices
Hot-Electron Devices
Photonic Devices
–
–
–
Light Emitting Diode (LED)
Semiconductor Laser (Laser Diode, LD)
Photodetector
•
•
–
–
Photodiode (PD), Avalanche Photodiode (APD)
Phototransistor (PT)
Solar Cell
Display Devices
•
•
Thin-Film Transistor LCD (TFT-LCD)
Organic Electroluminescence Display (OELD) or Organic Light Emitting Diode (OLED)
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Semiconductor Devices (continued)
•
Integrated Devices
– Passive Components
• IC Resistor, IC Capacitor, IC Inductor
– MOS Menory
•
•
•
•
•
•
•
Dynamic Random Access Memory (DRAM)
Static Random Access Memory (SRAM)
Nonvolatile Memory
Erasable-Programmable Read-Only Memory (EPROM)
Electrically Erasable-Programmable Read-Only Memory (EEPROM)
Flash Memory
Single-Electron Memory
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Carrier Drift
 Carrier Drift (飄移)
– Carrier transport in an applied electric
field
– vn = -nE
– vp = pE
– n (p): carrier mobility (移動率)
(cm2/V-s)
– Drift Current Density
J = (qnn + qpp)E
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Mobility and Resistivity (Conductivity)
-1 = L-1 + I-1
 = -1 = [q(n n + pp)]-1
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Carrier Diffusion
 Carrier Diffusion (擴散)
– The carriers tend to move from a
region of high concentration to a
region of low concentration.
– Diffusion Current Density
Jn = qDn (dn/dx)
Dn: diffusivity (diffusion coefficient)

Einstein relation: Dn = ( kT/q)n)
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Current Density Equations
•
Jn = qnnE + qDn (dn/dx)
•
Jp = qppE - qDp (dp/dx)
•
J = J n + Jp
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Carrier Generation and Recombination
Direct generation and recombination of electron-hole pairs:
(a)
at thermal equilibrium.
(b)
under illumination
Decay of photoexcited carriers
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Indirect Generation-Recombination Process
Indirect G-R process at thermal equilibrium
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The P-N Diode --- Under Thermal Equlibrium
P-type and N-type semiconductors before and
after the junction formed
A p-n junction with abrupt doping charges at the
metallurgical junction
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The P-N Diode --- Under Biasing Conditions
Current-voltage characteristics of a typical Si p-n junction
(a)
Thermal equilibrium
(b)
Forward-bias condition.
(c)
Reverse-bias condition
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The P-N-P Transistor
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The MOSFET
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The CMOS
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The Thin-Film Transistor
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