1. Chapter III Semiconductor Devices
半導體元件

2. Basic Building Blocks of Semiconductor Devices
(a) M-S Junction (b) P-N Junction (c) Heterojuction (d) MOS structure

3. Metal-Semiconductor Contact
Schottky contact
Rectifying contact
Schottky Barrier
M-S devices
Unipolar devices
High-speed devices
Ohmic contact
Non-rectifying contact
Specific contact resistance
The apace charge width in a M-S contact is inversely proportional to the square root of the semiconductor doping.The probability of tunneling through the barrier increases with the increasing doping concentration.
Electrodes
Energy-band diagram of a heavily doped n-semiconductor-to-metal junction

4. Schottky-Barrier Diode
M-S junction device
Unipolar device
Majority-carrier device
Without minority- carrier-storage effect
III-V compound semiconductors (GaAs)
Properities of devices:
High operation speed
Lower cut-in voltage
Higher saturation current

5. The P-N Diode --- Under Thermal Equilibrium
P-type and N-type semiconductors before and after the junction formed
A p-n junction with abrupt doping charges at the metallurgical junction

6. The P-N Diode --- Under Biasing Conditions
Current-voltage characteristics of a typical Si p-n junction
Thermal equilibrium
Forward-bias condition.
Reverse-bias condition

7. Classification of Semiconductor Devices
Bipolar Devices
P-N Junction Diode
Bipolar Junction Transistor (BJT)
Heterojunction Bipolar Transistor (HBT)
Thyristor and related power devices
Unipolar Devices
Schottky-barrier diode (SBD)
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)

8. 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)

9. 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
MEMS devices

10. The Bipolar Junction Transistor (BJT)

11. The MOSFET

12. The CMOS

13. To minimize parasitic capacitances
MESFET
Schottky Contact
Ohmic Contact
To minimize parasitic capacitances
Mesa Structure

14. MODFET Modulation Doped FET HFET (Heterojunction FET)
A thin undoped well bounded by two wider bandgap doped barrier
HFET (Heterojunction FET)
2DEG FET or TEGFET,
SEDFET (Separately Doped FET)
Advantages:
Extremely high cutoff frequency and fast access time

15. HEMT HEMT: Why HEMT? High Electron Mobility Transistor
250,000 cm2/V-s at 77K
2,000,000 cm2/V-s at 4K
Why HEMT?
In conventional MESFET:
Channel doping carrier number 
But mobility (impurity scattering)
 conductivity is limited (  = q n )
For HEMT:
Sheet carrier density is as high as 1012 cm-2 (~1020cm-3 for 10-nm thick channel layer)