Quiz-7 Solns

Quiz-7 Solns - Quiz #7: Solid-state Physics April 16, 2007...

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Quiz #7: Solid-state Physics April 16, 2007 SOLUTIONS Problem 1 GaN is a semiconductor with the band gap E g = 3.5 eV. Will it be n - or p -type after doping with Si? Explain why . Draw a band diagram for this case with appropriate labels. Include the dopant level and the Fermi level. It will be n-type if Si (IV group) preferably replaces Ga (III group) atoms in GaN crystal lattice, and it will be p-type if Si preferably replaces N (V group) atoms. In the first case Si impurities act as a donors Si Ga (source of free electrons), in the second – as acceptors Si N (source of free holes). Which case will be realized depends on several circumstances. Note that if you selected only one case and gave a good explanation, it was acceptable. Band diagrams for n- and p-type cases: x E E V E C E F E A p -type GaN electrons Problem 2 When the n -type GaAs sample with sizes l × w × t = 10mm × 2mm × 0.1mm is placed in a magnetic field B = 1 T, and a current I = 5 mA flows along its length l , a Hall voltage of 1 mV is measured across its width
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This homework help was uploaded on 04/22/2008 for the course PHYS 320 taught by Professor Baski during the Spring '04 term at VCU.

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