The present invention is a hetero superlattice pn junction. In particular, the invention combines n and p type superlattices into a single pn junction having a bandgap sufficient to create high frequency (i.e. blue or higher) light emission. Individual superlattices are formed using a molecular beam epitaxy process. This process creates thin layers of well material separated by thin layers of barrier material. The well material is doped to create carrier concentrations and the barrier materials are chosen in combination with the thickness of the well materials to adjust the effective bandgap of the superlattice in order to create an effective wide bandgap material. The barrier material for the n and p type superlattices is different from the material used to form either of the two types of well layers. A particular embodiment of the present invention forms a first superlattice from n type doped ZnSe well layers and undoped ZnMnSe barrier layers and forms a second superlattice from p type doped ZnTe well layers and undoped ZnMnSe barrier layers. The first and second superlattices are merged into a hetero superlattice pn junction. The thickness and composition of the individual well and barrier layers can be modified to adjust the effective bandgap of the pn junction. Therefore, a wide bandgap diode is formed from previously incompatible materials.