Calculating Electric Field from Electron Drift and Diffusion in Si Sample"

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orangeincup
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Homework Statement


A sample of Si, in which 0<=x<=(25*10^-4), electron concentration is n(x)=5*10^16 cm^-3) * exp(-x^3/2*10^-8), temperature is 300k and electron mobility is 1300 cm^2/V*s. The electron current through the Si has both drift and diffusion components and total electron current density through the sample is independent of x.

Find an expression for the electric field as a function of electron current density.
Evaluate the electric field at 10*10^-4 if the electron current density is 15 A/cm^2.
Evaluate the electric field at 10*10^-4 if the electron current density is 0 A/cm^2.

Homework Equations


Jn=e*n(x)*un*Ex+e*Dn*du/dx
Jn=pvd
Jn=(ep)vdp

The Attempt at a Solution


For the first part, I think I know how to solve if I can calculate Jn, since I have all the other values except Jn and Ex(which I need to solve for). Is there an equation which let's me solve for Jn with the values I have? Is there a constant I'm missing?
 

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Yeah I solved it, thanks