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

In summary, we have a sample of Si with a variable electron concentration, temperature, and electron mobility. The total electron current density through the sample is independent of x. We are asked to find an expression for the electric field as a function of electron current density and evaluate it at two different values of electron current density. To solve for the electric field, we can use the equations Jn=e*n(x)*un*Ex+e*Dn*du/dx, Jn=pvd, and Jn=(ep)vdp. However, we need to know the value of Jn, which we can calculate using the given values and equations.
  • #1
orangeincup
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0

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?
 
  • #3
Yeah I solved it, thanks
 

1. How do you calculate the electric field in a Si sample?

To calculate the electric field in a Si sample, you will need to use the drift and diffusion equations. These equations take into account the movement of electrons in the sample due to their drift and diffusion processes. By solving these equations, you can determine the electric field at any point in the sample.

2. What factors affect the drift and diffusion of electrons in a Si sample?

The drift and diffusion of electrons in a Si sample can be affected by several factors, such as the temperature of the sample, the concentration of impurities, and the applied voltage. These factors can alter the rate at which electrons move and therefore impact the electric field in the sample.

3. How does the drift and diffusion of electrons contribute to the overall electric field in a Si sample?

The drift and diffusion processes of electrons play a crucial role in determining the electric field in a Si sample. Electrons that are free to move due to thermal energy or an applied voltage will contribute to the overall electric field in the sample. The rate at which these electrons move and their concentration will determine the strength of the electric field.

4. Can the electric field in a Si sample be manipulated or controlled?

Yes, the electric field in a Si sample can be manipulated or controlled by adjusting the temperature, impurity concentration, or applied voltage. By varying these factors, you can change the rate of electron drift and diffusion, ultimately altering the electric field in the sample.

5. How does the calculation of electric field from electron drift and diffusion in a Si sample relate to real-world applications?

The calculation of electric field from electron drift and diffusion in a Si sample is crucial in understanding the behavior and performance of electronic devices such as transistors and solar cells. By accurately determining the electric field in a Si sample, scientists and engineers can optimize the design and functionality of these devices.

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