A hole current of 10-4 A/cm2 is injected into the side (x = 0) of a long N-silicon bar. Assuming that the hole flows only by diffusion, and that at very large values of x, the distribution of excess holes decays to zero. Determine, at T = 300 K:

a) The steady-state excess hole density at x = 0.
b) Repeat part (a) at x = 100 μm. Given μp = 400 cm2/V-s, μn = 1600 cm2/V-s, T = 300 K, and the lifetime of hole is 25 μs.