Prerequisite: EEL 5091 or consent of instructor
Textbook: Physics of Semiconductor Devices (3rd Ed.)
Key References: Device Electronics for Integrated Circuits (3rd Ed.)
R. S. Muller and T. I. Kamins with M. Chan
Physics of Semiconductor Devices
Fundamentals of Carrier Transport, 2nd Ed.
Electrons and Holes in Semiconductors
Fundamentals of Modern VSLI Devices
Content: This course teaches the basic physics of semiconductor devices, including the fundamental principles of pn junctions. The basic operation of the bipolar transistor is covered. (Basic MOSFET operation is covered in EEL 6390, but much of the underlying physics is presented in this course.)
The course begins with an overview of energy bands in semiconductors, particle concepts for electrons and holes, density of states, and effective masses. Next, properties of semiconductors in thermal equilibrium (e.g., Fermi-Dirac statistics) are described, leading to studies of nonequilibrium properties based on quasi-Fermi levels. The Boltzmann transport equation, and its moments, are used to discuss carrier transport, heating, and associated effects (e.g., velocity overshoot).
The basic properties of the pn junction are analyzed in depth. Main topics include Shockley's regional model and the concept of quasi-neutrality, pertinent boundary conditions related to both electrostatic and electrochemical (quasi-Fermi) potentials, high-level injection, current-voltage characteristics, and junction capacitance.
The bipolar transistor is analyzed generally, allowing for heterojunctions as in the SiGe-base HBT. DC properties at all current levels are characterized. Effects of heavy doping and polysilicon contacts on emitter efficiency are discussed, and base transport is described via the Moll-Ross formalism generalized to allow for spatially variable bandgap. High-current effects in the (epitaxial) collector (i.e., quasi-saturation) are described. Large-signal modeling is studied with emphasis on charge control and the quasi-static approximation. Small-signal modeling based on linearization is demonstrated, and frequency limits of the HBT are outlined.
2. 3D (in bulk) and 2D (in channel) density of states (delocalized)
B. Impurities (localized states)
2. Fermi-Dirac distribution (Fermi level)
4. Degenerate and nondegenerate carrier densities
5. Generalized Einstein relation
6. Heterostructures and energy-band distortion due to heavy doping
(bandgap narrowing, effective intrinsic carrier density)
d. Surface recombination velocities
3. Boltzmann transport equation, moments
(hot-carrier energy transport, velocity overshoot)
a. Heavy-doping and heterostructural effects
A. Quasi-neutrality (dielectric relaxation)
B. Shockley's regional model (Debye length)
C. QFL-based boundary conditions (voltage vs. potential)
D. Ambipolar transport equation; high-level injection
E. Current-voltage characteristics; SNS space-charge-region current