3 mev how good is this approximaon from sze and irvin

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Unformatted text preview: populated 19 Inferring Hole Poten[al & Kine[c Energy From Band Diagrams “k” Space E “Real” Space Electron Higher Potential Energy Electron Lower Potential Energy Hole Higher Potential Energy Hole Lower Potential Energy Comments: •  The location of the band edge is an indication of the potential energy •  The location above (or below for holes) the band edge is an indication of kinetic energy Hole Energy 20 Intrinsic Material •  A hole is created when thermal energy is transferred to an electron from the laqce and the electron is elevated from the valence band to the conduc[on band •  Electrons and holes present in equal concentra[ons, called the intrinsic concentra4on •  The intrinsic concentra[on increases with increasing temperature (more thermal energy) •  The intrinsic calcula[on is based upon thermal energy only – no light, current injec[on, etc. ri = α r n0 p0 = α r ni2 = gi ri gi What Happens if We Insert an Atom from Another Column? III II IV V VI Extrinsic Material Bohr Model for Approxima[on of Radius and Energy of Donor Electron Coulomb Force = Centripetal Force q2 mv 2 − =− 4πε r ε o r 2 r Orbital Angular Momemtum p = mvr = n Solve for Ground State Radius and Energy Effective Radius and Energy 4πε r ε o rd = * mn q 2 2 * 1 *2 mn q 4 E d = mn v = 2 2( 4πε r ε o )2 2 * GaAs(ε r = 13.1, mn = 0.067 mo ) * mn q 4 Ed = = 0.0053eV 22 8(ε r ε o ) h rd = 10.3 nm Note: The Lattice Constant of GaAs is 0.565 nm The energy required to excite the donor electron from the n=1 state to the free state...
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