1-21

1. Cubic crystals: (a) simple cubic; (b) face-centered cubic, an atom in the center of every face, and (c) body-centered cubic. Figure 1.21 1-21

2. (a) The diamond structure consists of two interpenetrating FCC lattices. The second FCC cube is offset by one-quarter of the longest diagonal. The dashed lines indicate the part of the second FCC lattice that is outside the unit diamond cell. (b) A zinc blende material has the same structure, but two types of atoms. The black atoms are one type (for example, gallium) and the colored atoms are the other (arsenic). Figure 1.22 1-22

3. The three most important crystallographic planes (in parentheses) and the corresponding crystallographic directions (square brackets). Figure 1.23 1-23

4. The density of states functions for electrons in the conduction band and the valence band. The density of states versus energy plot is superimposed on the energy band diagram (energy versus position x). Figure 2.11 2-11

5. The Fermi-Dirac distribution function gives the probability of occupancy of an energy state E if the state exists. Figure 2.12 2-12

6. The distribution of the electrons near the bottom of the conduction band, n(E), is the product of the density of states distribution S(E) times the probability of occupancy of states f(E) at a particular energy. The distribution of holes near the top of the valence band p(E) is the product of the density of states distribution times the probability of vacancy of states at a particular energy. (a) n type, (b) p type. Figure 2.13 2-13

7. The electron distribution function n(E) as a function of energy (energy on the vertical axis). Figure 2.17 2-17