Calculate the density of states of free electrons of energy 0.2 eV in silicon.
A) 8.16 x 1016 eV-1 cm-3
B) 9.45 x 1016 eV-1 cm-3
C) 10.72 x 1016 eV-1 cm-3
D) 12.38 x 1016 eV-1 cm-3