In a solar cell, when a photon is absorbed, an electron is ejected, leaving a vacancy known as a hole. The electron and hole are attracted to each other and are effectively stationary at the position of the original semiconductor atom until they are separated. The hole then becomes mobile and can carry a charge. Would you expect the drift speed of holes in a solar cell to be greater than, less than, or equal to the drift speed of free electrons in the metal wires connecting the solar cell to the electrical devices it powers?
a) Greater than
b) Less than
c) Equal to
d) It depends on the temperature