ECE 440 Homework 1 Fall 2010
Due: Friday class, September 3, 2010
Print your name and netid legibly. Show all work leading to your answer clearly and
neatly. Staple multiple pages. Put all units.
1. Answer the following questions as concisely as possible.
(a) Name (i) one elemental semiconductor and (ii) one Ⅲ-Ⅴ compound semiconductor.
(b) What is the difference between a crystalline and a polycrystalline material?
(c) How many atoms are there in a simple cubic unit cell? in a bcc unit cell? In a fcc unit cell?
in the unit cell characterizing the diamond lattice?
(d) 1Å =? cm
(e) In terms of the lattice constant a, what is the distance between nearest-neighbor atoms in a
simple cubic lattice?
(f) How many nearest-neighbor atoms are there in the diamond and the zincblende lattices?
2. The surface of a Si wafer is a (100) plane
(a) Sketch the placement of Si atoms on the surface of the wafer?
(b) Determine the number of atoms per cm2 at the surface of the wafer.
(c) Repeat parts (a) and this time taking the surface of the Si wafer to be a (110) plane.
(d) Repeat parts (b) and this time taking the surface of the Si wafer to be a (110) plane.
3. Treating atoms as rigid spheres with radii equal to one-half the distance between nearest
neighbors, show that the ratio of the volume occupied by the atoms to the total available
volume in the various crystal structure is
(a) π/6 or 52% for the simple cubic lattice.
(b)
3
π/8 or 68% for the body centered cubic lattice.
(c)
2
π/6 or 74% for the face centered cubic lattice.
(d)
3
π/16 or 34% for the diamond lattice.
