Charge distribution of diode in normal (un-biased) state
Apply the relation given below
n * p = ni2 at constant temperature (Mass action law)
Now we apply the above relation to p-type:
p i.e. the concentration of majority carriers (holes) is larger as doping of p-side is high and we have the value of ni2as constant at fixed temperature. Hence from the above relation we find that number of minority carriers ( electrons) is less in p-type material while as doping of n-side is normal, hence number of majority carriers (i.e. electrons) in n-side is not large with the value of ni2as constant and hence number of minority carriers is larger as compared to that in p-side. We depict the above as below:
Npo is defined as the concentration of minority carriers in N-type material i.e. holes and Pno is defined as the concentration of minority carriers in P-type material i.e. electrons when diode is in un-biased state (i.e. diode is neither forward biased or reverse biased).