20082ee2_1_final08 - ElectricalEngineeringDepartment...

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EE2 Final (Open Book and Notes) I. Silicon crystal has a diamond structure with a lattice constant of 5.43 angstroms (The length of the edge of the conventional unit cell). (a) Draw a conventional unit cell for silicon crystal and find out the distance between the nearest neighbors of silicon atoms. (5%) (b) Show the atomic configuration of the silicon. How to form the tetrahedral bonds? (5%) (c) Is silicon direct band or indirect band? Show a schematic band structure for silicon. (5%) (d) Is aluminum a donor or acceptor in silicon? Calculate the Fermi level if the aluminum concentration is 3 16 10 5 × cm . (5%) (e) Calculate the effective density of states for silicon valence band at room temperature if the hole effective mass is reduced by a factor of two. (5%) (f) Calculate the valence band effective density of states of a one dimensional silicon crystal such as a quantum wire at room temperature. (Hint: the 1-dim density of states is proportional to 2 / 1 ε , where is the energy measured from the band edge)(5%)
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This note was uploaded on 04/13/2010 for the course EE 2 taught by Professor Vis during the Spring '07 term at UCLA.

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20082ee2_1_final08 - ElectricalEngineeringDepartment...

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