Midterm Exam 1 ECE103 (WI-11) 2/3/2011 ALLOWED: Calculators and one 8.5”x11 page of notes (one side). Note you are required to turn in your page of notes with your exam. NOT ALLOWED: Textbooks, class notes, problem sets, etc. ATTEMPT ALL PROBLEMS AND SHOW ALL WORK! This exam has a maximum score of 100 points. You have 80 minutes to complete this exam. q = 1.60x10-19 C; k = 8.617x10-5 eV/K; m 0 = 9.11x10-31 kg; ε 0 = 8.85x10-14 F/cm; 1 μ m = 1x10-4 cm = 1x10-6 m; n i (Si, T=300K) = 1.0x10 10 cm-3 ; E g (Si at T=300K) = 1.12 eV; Lattice constant (a = 5.43 x 10-8 cm for Si). Density of States Effective masses of Si at 300K m * n = 1.81 m 0 and m * p = 0.81 m0 1. [40 points] Please describe Si crystals by answering the following questions – (i) How many valence electrons does a Si atom have? (ii) What kind of crystal structure (lattice and unit cell) does Si form? Draw (100) and (111) planes for Si lattice and find out the atomic density of Si atoms in each plane. (iii)
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