So, now we are calculating the intrinsic carrier concentration N i. In an intrinsic semiconductor, the number of electrons is equal to the number of holes. If we equate the number of electrons is equal to number of holes is called N i. This is called as intrinsic carrier concentration, intrinsic carrier concentration. So, by using mass action law, the mass action law, the product of number of electrons, the number of holes is equal to N i square. So, here I am trying to calculate the intrinsic carrier concentration by using the number of electrons and number of holes. In the previous videos we calculated the number of electrons available in the conduction band. The number of electrons can be written as 2 M star K B D by H square H square, H square root of 3 by 2 exponential, d c minus E f by K B D, similarly the number of holes, this can be written like this. So, this is the valency band, this is the conduction band, this is the intrinsic family level. I am writing with respect to this arrow, P is equal to 2 M star K B D by H square root of 3 by 2, I am writing number of holes, so minus E f minus E v by K B D. Here the difference in energy between the conduction band and the valency band is called energy gap, but difference in the energy level between the valency band and the conduction band is called energy gap. If you write this E n i square, if you write this one, this becomes 4, multiplying 24, 2 by K D by H square root of q M star M star root of 3 by 2 exponential, E v minus E c by K B D. So, the difference in energy level between valency band and the conduction band, this can be written as the energy gap. So, I will write 4, 2 by K D by H square root of 3 E m star M star root of 3 by 2 exponential minus E g by K B D. If you write the N i here, N i square, if you write N i, this becomes, if you cancel this, if you write all the parts, we will then do 2 by K B D, involvement constant, root of 3 by 2, E m star M star root of 3 by 4 exponential minus E g by 2 K B D. This expression is called as intrinsic carrier concentration. So, here 2 is a constant, this all the factors are constant, M e and M star root are constant. So, this is the effective mass of the electron, this is effective mass of the hole, all the parameters are constant. Finally, the N i is directly proportional to the exponential of minus E g by 2 K B D. So, how to calculate this? The N is equal to P is equal to N i, this is the intrinsic carrier concentration, by using the mass action law, the breadth of number of electrons, number of holes is equal to N i square. So, N i is equal to N product of N into B whole to half, I know the N, I know the B, so substitute in the formula that will get the intrinsic carrier concentration, that will get proportional to the exponential of minus E g by 2 K B D.