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Unformatted text preview: Lecture 7 Monday February 7 EE 332 Semiconductor Devices Problem Assignment 3.1, 3.2, 3.6 Chapter 3 Review Questions 2-8 Electrical Conduction In a circuit with resistance R or conductance G, ohm’s law is: G R GV V R I IR V 1 1 and = ⇒ = = = In terms of the electric field ξ (V/m) and current density J (A/m 2 ), ohm’s law is given in terms of the resistivity ρ ( Ω m) and conductivity σ (1/ Ω m): σ ρ σξ ξ ρ ρ ξ 1 1 and = ⇒ = = = J J Relation between Resistivity and Conductor Resistance L A L t A L R ρ = wt L R ρ = w Random Thermal Velocity and Drift Velocity Fig. 3.1 Force of Electric Field on an Electron x ce x x a m q F * = − = ξ * ce x x m q ξ a − = When the electrons collide with a phonon, ionized donor or acceptor atom, lattice defect, or impurity, the motion of the electron is randomized again, and the acceleration begins again. The acceleration after collision is: Average Drift Velocity at Time of Collision n ce x n dn t m q t a t t a * v ) (t v- (t)...
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- Spring '08
- Electron, Electric charge, Fundamental physics concepts, Drift velocity, mce nq tn