Pd and Ag are both FCC transition metals, yet they exhibit significantly different electrical resistivity (Pd=105nm,AB=16nm). Based on their band structures shown below, how can this difference be explained? (hint: how do m and relate?) Problem 2 Consider two semiconductor materials Si (band gap 1.1eV ) and GaP (band gap 2.2eV ), perfectly pure and without dopants (i.e. intrinsic semiconductors). Which do you expect to have a higher free carrier concentration (ni) at room temperature (assuming identical effective densities of states)? Explain why, using an energy diagram. Problem 3 A crystalline silicon sample is prepared containing boron at a level of 3 parts-per-million (atomic basis). a) Assume the dopants are fully ionized, and that the Si matrix contributes a negligible concentration of thermally-excited charge carriers. Calculate the density of free charge carriers ni in the crystal (in cm3 ). b) Are the free charge carriers electrons or holes? c) Draw a schematic energy band diagram for this material and label the valence band, conduction band, band gap, and the energy level associated with the boron impurity. Problem 4 Sometimes defects in a crystal can have "doping" effects. Cuprous sulfide ( Cu2S) without extrinsic dopants often exhibits Cu vacancies (missing Cu+ions). Would this have the effect of n - or p-doping, and why