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Unformatted text preview: cm . The dopant is a group V element that is an effective 15-3 dopant at room temperature. Before doping the electron and hole mobilities w ere found to be 1,800 cm /V-sec and 500 cm /V-sec respectively. After doping, these values reduce to 2 2 1,200 cm /V-sec and 200 cm /V-sec respectively. 2 2 G c For Si, E = 1.11 eV and N = 2.8 x 10 cm 19-3 v and N = 1.04 x 10 cm . 19 -3 (a) Does the Si become n-type or p-type after doping? (b) Why do the carrier mobilities decrease after doping? (c) Calculate the electron and hole concentrations at 300 K. doped (d) Calculate the conductivity F of the sample after doping. (e) Which carrier is the minority carrier and w hy is it called so? doped undoped (f) What is the ratio of F / F at 300 K. (g) Compute how far and tow ards w hich band the Fermi level has moved due to the doping. (h) What attributes of semiconductors does this problem point out?...
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This note was uploaded on 10/16/2010 for the course E SC 314 at Penn State.