Explain what a diffusion current is. how is the diffusion constant related to the electron mobility?

Answer and Explanation:

Diffusion current can be defined as the current that flows as a result of diffusion of charge carriers in a semiconductor device as a result of difference in the concentration of  holes and electrons in the both the regions (p and n) of the semiconductor device.

Depletion region of p-n junction is dominated by diffusion current.

The diffusion constant is directly proportional to the electron mobility and is given by the expression:

where,

= Diffusion coefficient

= electron mobility

= time of correlation

Therefore, other parameters being constant (say):

is directly propotional to

v=ir = 3x15 =45 v

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.