# quz1X _ sol - ECE 440: Quiz Section X (12:00 p.m.) Name:_...

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ECE 440: Quiz Section X (12:00 p.m.) Name:_______________________________ 1. (a) Classify solid type (Crystalline, Amorphous or Polycrystalline) of the following three material. i). A glass window; ii) A grown silicon ingot; iii). A diamond in a wedding ring (3 points) Ans: i). A glass window ─ amorphous ii) A grown silicon ingot ─ (poly)crystalline iii). A diamond in a wedding ring ─ (poly)crystalline (b) Draw a body-centered cubic (bcc). If the lattice constant of the bcc is L (Angstrom), what is the radius of the largest hard sphere that can fill the cube? (2 points) Ans: Using the Pythagorean theorem the distance from corner to corner is given by: ( ) ( ) ( ) L L L L 3 2 2 2 = + + So, the radius of the largest hard sphere will be L 4 3 . 2. The hole concentration in GaAs at T = 300 K is p 0 = 1 x 10 12 cm -3 and the intrinsic carrier concentration is 10 10 cm -3 . (a) Is this material n-type or p-type? (1 point) Ans: ( ) ( ) type p p cm p n n o o i o ⟨⟨ = = = 3 8 12 2 2 10 10 10 10

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## This note was uploaded on 10/14/2009 for the course ECE 440 taught by Professor Lie during the Fall '09 term at University of Illinois at Urbana–Champaign.

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quz1X _ sol - ECE 440: Quiz Section X (12:00 p.m.) Name:_...

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