Semiconductor Devices
Semiconductor Devices
Syllabus
Basic semiconductor physics: Solid state devices – History and its relevance in daily life, semiconducting material properties, elements of quantum mechanics, energy levels in atoms, energy band formation, bandgap and material classification, Concept of holes, effective mass. Density of states and Fermi level in Solids. Doping, Intrinsic and Extrinsic materials , Equilibrium carrier concentration. Temperature dependence of carrier density, E-k diagrams.
Carrier statics and dynamics: Thermal motion of carriers, Drift and Diffusion. Carrier scattering, mobility and diffusivity. Carrier transport under low electric fields. Conductivity and resistivity. Carrier statistics, Drift-diffusion transport, continuity equation, Poisson's equation and their solution. Drift and diffusion currents. Excess carriers in semiconductors. Generation and recombination of carriers.
P-N junctions: pn junction electrostatics, energy band diagram, static behaviour (space charge, built-in potential, depletion width, field profile). depletion approximation, electric field at the junction, p-n junction under forward & reverse bias. quasi-Fermi levels and minority carrier injection. ideal diode volt-ampere equation. Reverse bias breakdown- Zener breakdown, avalanche breakdown. Temperature effects and breakdown voltages. Depletion and diffusion capacitance. Reverse recovery transients. Metal/semiconductor junction – Ohmic and Schottky contacts.
Field-Effect Transistors: Qualitative analysis of field effect, JFET and its characteristics, Pinch off voltage and drain saturation current. MOS Fundamentals, energy bands and charge under different bias conditions, flatband/accumulation/depletion/inversion condition in MOS junction.Threshold voltage of a MOS device. MOSFET structure and operating principle. Derivation of I-V, gradual channel approximation, ID-VD and ID-VG relationships. Biasing of FETs and MOSFETs. Analysis of simple analog and digital circuits using JFETs & MOSFETs.
Bipolar Junction Transistors: Fundamentals of BJT operation, Simplified Structure, Electrostatics. Characteristics of the current flow across the base regions, Minority and majority carrier profiles. DC parameters and current components, base transport factor, Early Effect, charge control equation & current gain. The coupled Diode model (Ebers-Moll Model). I-V characteristics of CE/CB/CC configuration. Cutoff and saturation conditions. Base narrowing and base width modulation. BJT as an Amplifier and Switch.
Other semiconductor devices and latest development: Optoelectronic devices in daily life, optical absorption, photodetectors, solar cells, LEDs. Technology scaling and Moore’s law, qualitative understanding of Short channel effects – velocity saturation, channel length modulation, drain induced barrier lowering (DIBL), differences in IV characteristics of long and short channel MOSFETs, overview of modern FETs (FinFETs, tunnel FETs and nanowire transistors).
Books and references
B.G. Streetman and S. Banerjee, “Solid State Electronic Devices”; Sixth Edition, Prentice Hall.
Neamen, Donald A. Semiconductor physics and devices: basic principles. New York, NY: McGraw-Hill.
S. M. Sze, Physics of Semiconductor Devices, John Wiley.
Semiconductor Device Fundamentals, R. F. Pierret, Prentice-Hall.
Robert L Boylestad and Louis Nashelsky, Electronic Devices and Circuit Theory, Pearson.
Adel S Sedra, K C Smith and A N Chandorkar, Microelectronic Circuits: Theory and Applications, Oxford University Press.