Lect14 - Last week of Course Last week of Course Final...

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Unformatted text preview: Last week of Course Last week of Course Final Exam: Monday March 3 Review session: Sunday March 2 3-5pm Lincoln Hall Theater z Today Consequences of quantum mechanics z Metals, insulators, semiconductors, superconductors, lasers, . . . can be understood ONLY with quantum mechanics! Extra office hours (Sunday & Monday) HW6 due Sat. 8am; bonus survey ICES forms Consequences of Quantum Mechanics Effects on our everyday lives The big picture of science,technology, and the universe Overview Overview z Why do some solids conduct others do not others are intermediate z Metals, Insulators and Semiconductors understood with quantum mechanics! z Understood in terms of Energy Bands and the Exclusion Principle z Metallic conduction - a purely quantum phenomenon z Solid-state semiconductor devices z The electronic states in semiconductors - a purely quantum phenomenon z Transistors, lasers, . . . z The laser z Bosons and Fermions z Stimulated emission of photons a purely quantum phenomenon z Superconductivity z Electrical conduction with zero resistance! a purely quantum phenomenon z All the electrons in a metal cooperate to form a single quantum state z Supplement: FYI z Quantum mechanics in the universe z The smallest particles to neutron stars! Electron in a crystal periodic array of atoms Bands and Band gaps occur for all types Bands and Band gaps occur for all types of waves in periodic systems of waves in periodic systems Bands of allowed energies for electrons Bands Gap range of energy where there are no allowed states Light propagating through a periodic set of layers with different index of refraction an interference filter Photon Transmitted? Reflected? Layers with alternating index n 1 and n 2 Light propagating through a periodic layers Light propagating through a periodic layers Demonstration of Bands and Band gaps Demonstration of Bands and Band gaps Light propagating through a periodic set of layers with different index of refraction an interference filter Photon Transmitted? Reflected? Layers with alternating index n 1 and n 2 For certain wavelengths there is complete reflection If one period is /2, the transmitted amplitude from each layer is out of phase (no transmission) but the reflected amplitude is in phase (complete reflection) This is a stop band where light waves cannot propagate through many layers For other wavelengths there is complete transmission This is a pass band Light propagating through a periodic layers Light propagating through a periodic layers Demonstration of Bands and Band gaps Demonstration of Bands and Band gaps Light propagating through a periodic set of layers with different index of refraction an interference filter Photon Transmitted?...
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Lect14 - Last week of Course Last week of Course Final...

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