Unit 2204: Semiconductor Devices and Technology

1. Introduction to Semiconductor Materials

• Basic properties of semiconductors
  • Electrical conductivity and temperature dependence
  • Intrinsic vs. extrinsic semiconductors
• Energy bands and bandgap
  • Valence and conduction bands
  • Bandgap significance and types of semiconductors (direct vs. indirect)
• Doping techniques
  • Donor and acceptor impurities
  • N-type and P-type semiconductors

2. Semiconductor Carrier Statistics

• Charge carriers in semiconductors
  • Electrons and holes
• Fermi-Dirac distribution function
  • Probability of occupancy of energy states
• Carrier concentration
  • Intrinsic carrier concentration
  • Effect of doping on carrier concentration
• Carrier mobility and conductivity
  • Factors affecting mobility
  • Relationship between mobility, carrier concentration, and conductivity

3. PN Junction Diode Operation

• Formation of PN junction
  • Diffusion and drift currents
  • Depletion region and barrier potential
• Biasing of PN junction
  • Forward bias: reduction of barrier and current flow
  • Reverse bias: widening of depletion region and leakage current
• Current-voltage (I-V) characteristics
  • Diode equation
  • Breakdown mechanisms (Zener and avalanche)

4. Bipolar Junction Transistors (BJTs)

• Structure and construction
  • NPN and PNP transistor structures
• Modes of operation
  • Active, cutoff, saturation, reverse-active
• Current amplification
  • Current gain (β and α)
• Transistor configurations
  • Common emitter, common base, common collector
  • Input/output characteristics and applications

5. Field-Effect Transistors (FETs)

• Types of FETs
  • Junction FET (JFET)
  • Metal-Oxide-Semiconductor FET (MOSFET)
• Operation principles
  • Channel formation and control by gate voltage
  • Depletion and enhancement modes
• Applications in electronic circuits
  • Amplifiers, switches, digital logic

6. Semiconductor Device Fabrication Techniques

• Photolithography
  • Masking and pattern transfer
• Doping processes
  • Diffusion and ion implantation
• Oxidation
  • Thermal oxidation to form SiO2 layers
• Etching techniques
  • Wet and dry etching
  • Role in patterning devices

7. Semiconductor Device Characterization

• Electrical measurements
  • Current-voltage (I-V) characterization
  • Capacitance-voltage (C-V) profiling
• Reliability testing
  • Stress tests and lifetime estimation
• Failure analysis
  • Identification and diagnosis of device failures

8. Optoelectronic Devices

• Light-emitting diodes (LEDs)
  • Operating principles and materials
  • Applications
• Photodiodes
  • Photodetection principles
  • Types: PIN, avalanche photodiodes
• Laser diodes
  • Stimulated emission and cavity design
  • Applications in communication and sensing

9. Semiconductor Device Scaling and Future Trends

• Moore's Law and device scaling challenges
  • Short channel effects
  • Heat dissipation and quantum effects
• Advancements in nanotechnology
  • Nanowires, quantum dots, 2D materials
• Emerging semiconductor technologies
  • FinFETs, Tunnel FETs, spintronics
  • Flexible and organic semiconductors