Homework in Solid state material

[Blond Arrow]

Here is the problem:

The electron concentration in a region of silicon depends linearly on depth with concentration of 5x10^15 cm^-3 at surface (x=0) and 10^15 cm^-3 at depth of x=500nm. If the vertical electron current density in this region is constant at Jn=100 A/cm^2, calculate the electric field near x=500nm. assume that the mobility is constant at 1250cm^2/Vs.

If anyone can at least explain the meaning of each value written in the problem and the formula that can be used to solve this problem ..

Thank you...

 

[Blond Arrow]

No one know?

 

[uart]

The equation that you need is for the total electron current density (drift plus diffusion).

J_n = q D_n \frac{dn}{dx} + q \mu_n E

q = 1.6E-19

D_n = (kT/q) u_n which is approx 0.026 u_n at room temperature.

Since you know J_n and dn/dx then E is the only unknown.