Excess carrier concentrations and diffusion current density

Consider a bar of p-Si that is homogeneously doped to a value of 3x10^15 at T=300K.  The applied electric field is zero.  A light source is incident on the end of the semiconductor.  The excess-carrier concentration generated at x=0 is deltap(0)=deltan(0)=10^13/cm^3.  Neglect surface effects.  Mun=1200/cm^2/Vs.  Mup=400/cm^2/Vs.  Taun=5*10^-7s.  Taup=10^-7s.

(a) Calculate the steady state excess electron and hole concentrations as a function of distance into the semiconductor.
(b) Calculate the diffusion current density as a function of x.


What are the solutions, and how did you get them?

Thanks