Solid State Physics

General Foundation

The course is also offered to exchange programme students.

Upon successful completion of the course, students will be able to: - Describe the structure of solid materials, including bonding types, basic crystal structures, and the concept of the reciprocal lattice. - Analyze the dynamics of atoms in crystals, explain the concept of phonons, interpret dispersion relations and the phonon density of states, and relate these concepts to the thermal properties of solids using the Einstein and Debye models. - Ιinterpret the electrical conductivity of metals by applying the classical Drude model and understand fundamental transport phenomena such as carrier scattering and the Hall effect. - Understand the quantum mechanical description of electrons in solids, examining the formation of energy bands, the electronic density of states, and the role of the Fermi energy. - Analyze the electronic properties of semiconductors, both intrinsic and extrinsic, taking into account temperature, carrier effective mass, and scattering mechanisms. - Describe the dielectric and optical properties of solids, explaining light–matter interactions involving electrons and phonons through models such as those of Lorentz and Drude.

- INTRODUCTION (4 hours): Chemical Bonds in solids, crystal structure of solids, basic crystal structures, determination of crystal structure, reciprocal lattice. - LATTICE DYNAMICS (8 hours): Lattice vibrations in one dimension, monoatomic and diatomic chains, dispersion relations and curves, phonon density of states, normal modes of vibrations and phonons, lattice dynamics in three-dimensions, experimental methods for the determination of phonon dispersions. Problems. - THERMAL PROPERTIES OF THE LATTICE (6 hours): Specific heat — Einstein and Debye models, anharmonic effects and thermal expansion, lattice thermal conductivity. Problems. - ELECTRONIC PROPERTIES OF METALS—CLASSICAL APPROACH (12 hours): Drude classical model of electrical conductivity, relaxation time and mean free path, electrical conductivity and mobility, Hall effect for measuring carrier concentration and type, electron scattering centers and their effect on electrical conductivity and resistivity (Matthiessen’s rule), Wiedemann-Franz law. Problems. - ELECTRONIC PROPERTIES OF SOLIDS—QUANTUM APPROACH (6 hours): The Sommerfeld-Bethe model and its differences from the nearly free electron and tight-binding approximations, the dispersion relation E(k) for a free electron and for an electron in a periodic, time-independent potential, calculation of the density of states, the Fermi energy, the electronic specific heat in metals, band structure of selected metals. Problems. - SEMICONDUCTORS (8 hours): Direct and indirect bandgap semiconductors, dopants (donors and acceptors), degenerate semiconductors, effective mass of carriers, temperature effects on bandgap and carrier concentration, the position of the Fermi level within the band gap (its variation with temperature and the effective masses of the carriers), carrier concentration in intrinsic semiconductors and law of mass action, variation of carrier concentration as a function of temperature in doped semiconductors, carrier scattering in semiconductors and mobility temperature dependence, band structure of selected semiconductors. Amorphous semiconductors. Problems. - DIELECTRIC AND OPTICAL PROPERTIES OF SOLIDS (8 hours): Introduction to light-matter interaction, refractive index and dielectric function, optical properties of various types of materials, classical light-solid interaction (Lorentz model), multiple resonances, the concept of local field in dielectrics, interaction of light with free electrons in metals (Drude model), infrared interaction with phonons, Lyddane-Sachs-Teller relation and Reststrahlen band, polaritons, other dielectric phenomena (impurities, piezoelectricity, dielectric breakdown). Problems.

Crystal structure, reciprocal lattice, phonons, lattice dynamics, thermal properties of solids, specific heat and thermal conductivity of solids, electrical conductivity of crystalline solids, Fermi energy, density of electronic and phononic states, semiconductors, Hall effect, electronic structure of solids, dielectric function, optical properties of materials.

23-07-2025