ENG 2002 Lecture Notes - Charge Carrier, Dopant, Indium
2 Apr 2014
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Solutions to chapter 8 problems on semiconductors: in general, assume 1010 free electrons / cm3 in si at 300k. Thus some small portion of electrons have energies greater than 1. 1ev which allows them to break free of their bonds and leave the valence band for the conduction band: there are 4 valence electrons in one si atom. At room temperature, there are about 1010 free electrons in cm3. So, 1010 (free) electrons/4x1022 (total valence) electrons = 1/4,000,000,000,000: doping adds electrons or holes, increasing the number of majority charge carriers. Number of dopant atoms in heavily doped si/cm3 = 1020. Number of free electrons in pure si at room temperture/cm3 = 1010 in , we can take. 3cm , since it is much larger than. Since this is still >> ni, the concentration of majority carriers is: The concentration of minority carrier: (1. 5 1010)2 p0 =
