Learning objectives
The aim of this course is providing the students with the basic knowledge of the fundamental physical mechanisms underlying the operation of the most important low-power and high-power semiconductor devices.
Prerequisites
The student must be familiar with the notions of mathematics, phyiscs, chemistry, electrical and electronic engineering provided by the Laurea course in Electronic Engineering.
Course unit content
1) Basics of semiconductor physics.
Semiconductors under equilibrium conditions. Mass action law. Fermi-Dirac and Maxwell-Boltzmann distributions. Free carriers, mobility, saturation velocity. Drift-diffusion model.
2) Metal-semiconductor junctions.
Metal-semiconductor junction under equilibrium conditions. Image-force barrier lowering. I-V characteristics. Ohmic contacts.
3) PN and PIN junctions.
Non-uniform doping distributions. The PN junction at equilibrium. Debye length. Reverse bias. Capacitance of a reverse-biased diode. Avalanche and Zener breakdown. Continuity equations. Shockley-Hall-Read recombination. Auger and surface recombination. I-V characteristics of the PN diode. Long-base and short-base diodes. Validity of the low-injection and quasi-equilibrium approximations. Currents in the space-charge region. G-R currents in forward and reverse bias. Switching transients. Diffusion capacitance. P-i-N diodes: structure and static and dynamic characteristics.
4) Bipolar Junction Transistors (BJTs).
Forward-active region. Base transport factor. Emitter efficiency. BJT switching behavior. Ebers-Moll model. Early effect. Integrated BJTs. Low-current effects. High-injection effects: Kirk effect, base resistance. Base transit time. Charge-control model. Small-signal model. Frequency limitations: fT and fMAX. Substrate and lateral pnp transistors. Power BJTs: Structure, static and dynamic characteristics.
5) Thyristors (SCRs) and GTOs.
Structure, static and dynamic characteristics.
6) MOS Transistor (MOSFET).
Ideal MOS systems. Band structure. Accumulation, depletion, inversion, strong inversion. Threshold voltage and body effect. C-V characteristics of the ideal MOS system. Non-ideal MOS systems: cahrges in the oxide and at the interface. MOS transistors. Body effect. Bulk charge effect. Threshold voltage adjustment. Sub-threshold current. Short-channel and narrow-channel effects. Source/drain charge sharing. Drain-induced barrier lowering. Sub-surface punch-through. Mobility reduction. Velocity saturation. Drain current in short-channel MOSFETs. Effects of scaling on short-channel MOSFETs. Electric field in the saturated velocity region: quasi-2D model. Hot carrier effects: substrate and gate currents. Power MOSFETs: Structure, static and dynamic characteristics.
7) IGBTs.
Structure, static and dynamic characteristics.
8) Compound semiconductor and heterostructure devices (hints).
MESFETs, HEMTs, PHEMTs, HBTs.
9) Optoelectronic Devices.
Optical properties of semiconductors. Photocurrent in a pn diode. Conductive photodetectors. P-i-N photodetectors. Avalanche photodiode. Phototransistor. Metal-semiconductor detectors. LEDs. Lasers.
Bibliography
Suggested textbook
1) R. S. Muller, T. I. Kamins, P. K. Ko, “Device Electronics for Integrated Circuits,” 3rd Edition, John Wiley & Sons, 2003. ISBN: 0-471-42877-9.
2) J. Singh, "Semiconductor Devices - An Introduction," McGraw-Hill, 1994, ISBN: 0-07-057625-4.
3) N. Mohan, T. M. Undeland, W. P. Robbins, “Power Electronics: Converters, Applications, and Design,” 3rd Ed., John Wiley, 2003.
Other useful books
1) W. A. Harrison, “Applied quantum mechanics,” World Scientific, 2000, ISBN: 9810243758.
2) P. Hofmann, "Solid State Physics - An Introduction," Wiley-VCH, 2008, ISBN: 978-3-527-40861-0
