Holes will experience a force in the y direcon right

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Unformatted text preview: Ÿ༉ Ÿ༉ Ÿ༉ Ÿ༉ Ÿ༉ Ÿ༉ Ÿ༉ Ÿ༉ Ÿ༉ Ÿ༉ Ÿ༉ Ÿ༉ Ÿ༉ Ÿ༉ 18 Effects of Both Temperature and Impurity Concentra[on on Mobility µ (cm 2 /V − s) Nd-Na = 1015 cm-3 Nd-Na = 1017 cm-3 1 1 1 1 = + + + ... µ µImpurity µLattice µDefect Nd-Na = 1019 cm-3 µImpurity ∝ T 3 / 2 300K T(K)-log scale At T=300K •  For Nd- Na=1019cm- 3, the µ Lattice ∝ T −3/2 mobility is dominated by impurity sca5ering •  For Nd- Na=1017cm- 3, the mobility is dominated by impurity sca5ering •  For Nd- Na=1015cm- 3, the mobility is dominated by lapce sca5ering 19 Mobility Temperature Dependence Mobilities Add Inversely: 1 1 1 1 =+ + + ... µtot µ1 µ2 µ 3 → like parallel inductors! 20 Comparison With Measured Data http://www.globalsino.com/micro/1/1micro9936.html 21 Sca5ering Mechanisms in GaAs 22 Bonus Material Satura[on of Drih Velocity •  •  Ohmic region: carrier drih velocity is propor[onal to electric field High field region: current saturates due to satura[on of the drih velocity –  Addi[onal field force is directly offset by increased sca5ering –  Addi[onal energy is transferred directly to the crystal lapce –  Mean thermal velocity at 300K is ~107 cm/s in silicon –  A “hot electron” has a velocity exceeding the mean...
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This note was uploaded on 03/06/2014 for the course ECE 340 taught by Professor Leburton during the Spring '11 term at University of Illinois, Urbana Champaign.

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