In the context of p−n junction (i) The barrier potential decreases under forward bias, since both potentials are in opposite direction. (ii) A ideal p−n diode work as zero resistance conductor under forward bias (iii) The barrier potential increase in reverse bias, due to the same polarity of potentials of barrier potential and biasing battery. (iv) Width of depletion region depends on the doping level in p -type and n -type.