20082ee2_1_homework%202_08

20082ee2_1_homework%202_08 - VI. The conduction band of...

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . EE2 Physics for Electrical Engineers Homework #2 I. What is energy band theory? Does the theory require that electrons are waves? II. Explain the differences in conductivities in metal, insulators, and semiconductors. III. Silicon has a diamond structure with a lattice constant of 5.43 angstroms ( the length of the edge of the conventional unit cell). How many silicon atoms do you have in a 1 3 cm cube of silicon crystal? Calculate the weight of this silicon cube given that the atomic mass of silicon is 28.09. IV. What are direct semiconductor and indirect semiconductors? Give two examples for each type. V. GaAs has a energy band gap of 1.43 eV. Find out the photon wavelength of a laser made of GaAs. Is it visible?
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Unformatted text preview: VI. The conduction band of GaAs has an effective mass of 0.067 m , where m is the free electron mass. Find out the curvature of the conduction band at the band edge. VII. If the electron in GaAs is accelerated from rest by an electric field of 1 kV/cm in 2 picoseconds, find out the final velocity of the electron and how long it has traveled. VIII. From the atomic configuration of copper and energy band theory, explain haw many valence electrons per atom is making contribution to the conductivity of copper crystal? --END-- Electrical Engineering Department The Henry Samueli School of Engineering and Applied Science University of California, Los Angeles Dee-Son Pan pan@ee.ucla.edu Phone (310)-825-1123 Spring 2008...
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This note was uploaded on 04/13/2010 for the course EE 2 taught by Professor Vis during the Spring '07 term at UCLA.

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