Location of the band edge is an indication of the

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Unformatted text preview: E Γ e Eg=1.43eV Ec k Ev Heavy Hole Valence Band Ge Si mn* 0.55mo 1.1mo GaAs 0.067mo mp* 0.37mo 0.56mo 0.48mo A Few Cau[ons •  The topic of effec[ve mass is more complicated than can reasonably be presented in an introductory course (treatment as tensor in higher level courses) •  Make sure you know what effec1ve mass to use and how to use it based upon what you are calcula1ng •  Calcula[on of the carrier concentra[on uses the density of states effec1ve mass –  For Silicon, the density of states effec[ve mass is (mn*)3/2 = 6(mlmt2)1/2 –  This comes from the 6 indirect valleys, and the ellip[cal shape of those valleys –  Direct- gap materials such as GaAs have a single minima, so just the effec[ve mass is used •  Conduc1vity effec1ve mass is different than the density of states effec[ve mass for Silicon * 3 mn = ( 1 1 1 + +) ml mt mt •  Cyclotron effec1ve mass is also different •  There is further complica[on around the direct- indirect crossover in a material where mul[ple valleys can be...
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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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