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Unformatted text preview: 1 EE360 Lecture 7 Carrier Concentrations and Carrier Action Objective: Be able to calculate carrier concentrations and currents in semiconductor devices. Questions to be Answered: Review: How does drift describe carrier motion? What do we mean by carrier mobility How do we calculate resistivity of a material, and the resistance of an object? EE360 Lecture 7 Review: Carrier Drift Drift : motion of electrons and holes in response to an electric field. Recall from our discussion of effective mass: Electron motion in a vacuum: Electron motion in a crystal: Where E is the electric field, and v is the velocity BUT, we need to account for collisions with the semiconductor atoms and impurity atoms dt d m q F v = = E dt d m q F n v * = = E 2 EE360 Lecture 7 Review: Carrier Drift (continued) Positive charges, holes, are accelerated in the direction of the electric field, negative charges, electrons, are accelerated opposite the electric field. Scattering from the lattice atoms or impurity atoms repeatedly decelerates the carriers and changes their direction....
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This note was uploaded on 04/20/2008 for the course EE 360 taught by Professor Hastings during the Spring '08 term at Kentucky.
- Spring '08