Calculate the Diffusion lengty

[Elekko]

I'm wondering how this actually can be solved since i think there is one piece missing.

Homework Statement

Determin the diffusion length L on a P+N diode with Nd = 10^16 cm^-3 in the N region.

Homework Equations

Known is that Diffusion length can be found from L=sqrt(Dt)

The Attempt at a Solution

As D = kT/q*u where u can be determined using a electron and hole mobility graph.
But now how can i find t?
It is not staded what t is.

 

[mark726]

Can you provide more information about the problem?

Thank you for your inquiry. I can see why there may be some confusion about finding the diffusion length in this scenario. The missing piece that you mentioned is actually the time (t) in the equation L=sqrt(Dt). In this case, t represents the time it takes for the diffusion process to occur.

To find t, we can use the equation t = x^2/2D, where x is the distance the dopants have diffused and D is the diffusion coefficient. In this problem, we are given the dopant concentration (Nd) and can use the diffusion coefficient for silicon (D = 10^-5 cm^2/s) to solve for t.

Once we have t, we can plug it into the equation L=sqrt(Dt) to find the diffusion length (L). I hope this helps clarify the process for finding the diffusion length in this scenario. If you have any further questions, please don't hesitate to ask. Best of luck with your calculations!