Unformatted text preview: lectrons in the y
direction will equal zero and no deflection of the
current will occur.
– Electrodes at either side of the SC can be used to
measure the voltage resulting from Ey otherwise
known as the Hall voltage.
– The text derives an expression for the Hall
coefficient, which is the inverse of the hole
concentration times the charge.
concentration The Hall Effect The Hall effect - graphically The Fermi Level at Equilibrium
• General Rule: No discontinuities or gradients can
exist in the equilibrium Fermi Level.
– Two different materials in intimate contact
• No external fields or thermal gradients so no net charge flow – As such energy is conserved, so electrons moving from
one material to the other are countered with equivalent
electrons going the other way (charge balance)
– Analysis of filled and empty states in each material
using Fermi-Dirac statistics will show that (with a bit of
algebra) f(E1) = f(E2).
– Recall that a filled state is represented by f(E) and thus an empty
state by 1- f(E).
state – This requires that EF1 = EF2 The Fermi Level at Equilibrium Two materials in intimate contact at equilibrium. Since the
net motion of electrons is zero, the equilibrium Fermi level
must be constant throughout....
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- Spring '10
- Electrons, Carrier Concentrations, E Fields, Lattice Scattering