Question

You find a sample of silicon, but the accompanying data sheet has been partially destroyed so you only know that it is n-type, its resistivity is 100 Ohm-cm, and its electron mobility is 1600 cm²/V-s. You also remember that n_i (Si) = 10¹⁰ cm ^-3 .

ii) What is the approximate equilibrium hole concentration, p_o, in this sample?

Answer 1

We know the Ohm's law : where is current Density is conductivity and is applied field.

Here Conductivity where is electron charge is electron concentration is mobility.

we can write this because it is a n-type semiconductor and we can approximate that current is largely carried by only electrons.

From here we can Estimate electron concentration to be :

Where is resistivity.

For Extrinsic Semiconductor. By law of mass action we get :

This is a good approximation and we get by substituting the numerical values mentioned in question :

The answer is :