A computational analyse of Poisson's equation relating normalised potential with normalised position for a heavily doped high–low junction at equilibrium is made. This is accomplished by choosing a model where both the sides are assumed to be heavily doped with one side having a relatively lighter doping in comparison to the other side. Variations of potential and majority carrier density against position are studied taking into account the effects of band gap narrowing and carrier degeneracy. The results are shown graphically. Copyright © 1991 WILEY‐VCH Verlag GmbH & Co. KGaA