Syllabus – EE 601

Semiconductor device physics.

Fall. Mon/Wed

A. F. J. Levi.

Outline and course content

This course is designed for those with an interest in the fundamentals and limitations of operation of contemporary electronic and photonic components used as the building blocks for more complex circuitry. The course emphasizes calculation of useful parameters relevant to the design and operation of practical and research devices such as scaled transistors, scaled lasers, and behavior of new materials with extraordinary behavior.

Novel combinations of materials and heterogeneous components will likely evolve, changing the design paradigm and requiring knowledge and insight that this course aims to provide. In addition to fundamental aspects of device physics, the use of optimization techniques to explore material properties and geometries for device design will be introduced.

Knowledge to the level of EE506 and EE539 is helpful, but not a prerequisite for this course. Recommended reference books are “Applied Quantum Mechanics” ISBN-10: 1009308076, “Optimal Device Design” ISBN-10: 0521116600, “Essential Electron Transport for Device Physics” ISBN: 978-0-7354-2158-5, and “Essential Classical Mechanics for Device Physics” ISBN: 978-1-6817-4412-4, which is free to download for USC students and at many other universities.

Some material covered by this course does not appear in any textbook.

Course content to include:

Review of existing and emerging materials, geometries, and devices. Semiconductors for FET, BJT, HBT, Laser diode, photodiode, APD, FPA. Use of 3D, 2D, 1D, and 0D. Metals and cold metals.

Review of material engineering and atomic potentials. Essential resources and control methods for engineers using quantum mechanics. Bonding, Bloch theorem and band structure in a lattice. Tight binding model and complex band structure. Quantum engineering and optimization of density of electron states. The Landauer transport model. Electron transport on a lattice. Role of complex band structure in determining electron wave packet tunneling. Quantum engineering and optimization of a semiconductor heterostructure diode current-voltage characteristics. Negative differential resistance at a “cold metal” interface.

Concepts from classical mechanics and electromagnetism. Charge conservation. Polarization, capacitance, and inductance. Classical electromagnetism and numerical solution of Maxwell equations. Radiation and waveguides. Conservative and non-conservative systems. The harmonic oscillator. Lattice vibrations. The damped driven oscillator. Methods of control. Origin of noise, fluctuation-dissipation theorem, and diffusion. Einstein relation. Lorentz model of light-matter interaction. The Kramers-Kronig relations. Propagation of electromagnetic waves in a dielectric medium. Complex dispersion relation and complex refractive index. The loss function.

Introduction to electron transport. The Drude model. DC and AC conductivity. Kinetic inductance.

Loss function. Permittivity of metal. The loss function of copper. Physical origin of plasma frequency. Local response in the Drude model. An electromagnetic field interacting with a metal. Drude dispersion of electromagnetic radiation. Changing the properties of a metal. Metal and electromagnetic fields in integrated circuits. Doping in semiconductors, metal-insulator transition and r_s^*.

Electron transport. Bloch oscillations. Material parameters contributing to current. Velocity-field characteristics and electron transfer to subsidiary minima. The Gunn diode oscillator. Ballistic transport.

The Boltzmann transport equation including conductivity and diffusion in the relaxation-time approximation. Evolution of the distribution function with time. The scattering term. Relaxation time approximation. The diffusion term. Mean free path and scattering time from mobility. Mean free path and scattering time in 2DEG. Electron optics in the 2DEG. Diffusion in devices. Diffusion and recombination of minority carriers. The Schottky barrier. Depletion width. Thermionic emission. Capacitance as a function of voltage bias.

Electron scattering in semiconductors. The electron-phonon interaction. The Frohlich interaction. The longitudinal polar-optic phonon scattering rate. The LO phonon scattering rate in the conduction band of GaAs. Energy and momentum conservation. Electron scattering rate from linear dielectric response. Coupled plasmon-phonon scattering. Scattering rates and fluctuation dissipation.

The Field Effect Transistor. Device modeling. Physical performance limitations. Tunnel-FET concept and lessons learned. CNT and graphene FET device design, performance metrics, and SPICE models.

Introduction to Coulomb scattering from ionized impurities. Elastic scattering of electron from ionized impurities in GaAs. Engineering correlation effects due to spatial position of dopant atoms. Estimating mean free path and mobility. Calculating the screened potential and dielectric function in wave vector space. Comparison between Thomas-Fermi screening and RPA.

Lindhard dielectric function. Application to metals and semiconductors. Single particle excitations and coupled plasmon–phonon collective excitation spectrum. Analysis of semiconductor dielectric function and use of MATLAB example code.

Calculation of electron lifetime and device design. Calculation of electron lifetime in unipolar transistors. Temperature dependence of non-equilibrium electron scattering rates. Non-equilibrium electron spectroscopy.

Numerical determination of non-equilibrium electron scattering rates. MATLAB code example. The truncated parabola of integration. Phase-space and its influence on scattering rate. Evaluation and interpretation of temperature dependence.

Non-equilibrium electron transport in bipolar transistors. Theory of minority carriers in conduction band interacting with majority carriers in valence band. Collective and single-particle excitation spectral function in three-band model. Calculation of scattering rates. Parabola of integration. Phase-space and device scaling. Experimental evidence that non-equilibrium electron transport dominates the static and dynamic performance of scaled HBTs.

The semiconductor laser and scaling. Influence of electron and photon quantization on static and dynamic behavior of scaled laser diodes and photon statistics. Failure of the non-equilibrium phase-transition description of laser light emission in scaled devices. Meso-scale lasers. The single quantum dot laser. Cavity QED and non-classical light. MATLAB models of laser behavior.

Examinations:

There are two written examinations, each of which will contribute 20% to the final grade. Presentation of a research paper contributes 50% of the final grade. The remaining 10% is for written solutions to written homework problems.

Statement for Students with Disabilities

Any student requesting academic accommodations based on a disability is required to register with Disability Services and Programs (DSP) each semester. A letter of verification for approved accommodations can be obtained from DSP. Please be sure the letter is delivered to me (or to TA) as early in the semester as possible. DSP is located in STU 301 and is open 8:30 a.m.–5:00 p.m., Monday through Friday. The phone number for DSP is (213) 740-0776.

Statement on Academic Integrity

USC seeks to maintain an optimal learning environment. General principles of academic honesty include the concept of respect for the intellectual property of others, the expectation that individual work will be submitted unless otherwise allowed by an instructor, and the obligations both to protect one’s own academic work from misuse by others as well as to avoid using another’s work as one’s own. All students are expected to understand and abide by these principles. Scampus, the Student Guidebook, contains the Student Conduct Code in Section 11.00, while the recommended sanctions are located in Appendix A:

http://www.usc.edu/dept/publications/SCAMPUS/gov/. Students will be referred to the Office of Student Judicial Affairs and Community Standards for further review, should there be any suspicion of academic dishonesty. The Review process can be found at:

http://www.usc.edu/student-affairs/SJACS/.

Electrical Engineering Semiconductor Device Physics

Syllabus – EE 601