Abstract The behaviour of both majority and minority carriers in a p +- s- n + epitaxial diode (where s may be p or n) has been investigated in this paper. Forward current-voltage characteristics of the diodes are obtained by exact numerical analysis, taking into account the effects of energy-gap narrowing, Auger recombination and carrier-carrier scattering. As with previous authors, it is found that the forward current increases with increasing middle layer thickness. The present analysis shows that such increase occurs only upto a specific applied bias, after which the forward current decreases with increasing middle layer thickness. This behaviour is attributed to double reflection, i.e. the reflection of both majority and minority carriers by the p- n junction and high-low junction respectively. Beyond the specific bias so determined, junction reflection loses its effectiveness. Distribution of carrier concentration and junction voltages for several device configurations are given to illustrate these features. The majority carrier reflection by the p- n junction is found to have a dominating effect in all cases.