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 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) Introduction.
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 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.
4) Bipolar Junction Transistors (BJTs).
Forward-active region. Base transport factor. Emitter efficiency. BJT switching behavior. Early effect. Integrated BJTs. Low-current effects. High-injection effects: Kirk effect, base resistance. Base transit time. Frequency limitations: fT and fMAX. Substrate and lateral pnp transistors.
5) 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.
6) Basics of semiconductor physics.
Energy bands in semiconductors. Charge carriers. Thermal equilibrium. Current transport.
7) Solar cells.
8) LEDs.
Full programme
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Bibliography
Suggested textbooks
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
D. L. Pulfrey, "Understanding modern transistors and diodes," Cambridge University Press, 2010. ISBN: 978-0-521-51460-6.
Other useful books
W. A. Harrison, “Applied quantum mechanics,” World Scientific, 2000, ISBN: 9810243758.
P. Hofmann, "Solid State Physics - An Introduction," Wiley-VCH, 2008, ISBN: 978-3-527-40861-0
Teaching methods
The course consists in a series of classroom lectures.
Assessment methods and criteria
Oral exam.
Other information
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