2. A Si crystal that is 2cm³ in size has been n-type doped uniformly at a ratio of

1 in 105. The intrinsic concentration of silicon is 1 x 10¹0 cm³ and its atomic

concentration is 5 x 1022 cm³. Figure 1 shows how the drift mobility varies

with dopant concentration at room temperature (300K).

a) What is the donor concentration?

b) What is the hole concentration?

c) Using the graph in Figure 1 and your answers to a) and b), calculate the

electrical resistance of the n-type doped silicon crystal.

d) We now dope the silicon crystal with boron atoms instead of arsenic to

create a p-type semiconductor. We again doped the crystal uniformly at a

ratio of 1 in 10 What is the electrical resistance now? Compare your

result to that obtained in c), giving a reason for any difference.