We report the fabrication and characterization of a vertical pn power diode which is realized using two separate epitaxial-growth mechanisms:(a) p-GaN over p-(4H)SiC,and(b) p-GaN over n-(4H)SiC with AlN as the interface layer.In all of the cases,n~+-doped(4H)SiC serves as the cathode substrate.Pd(200 A)/Au(10000 A) is used for the anode contact while Ni(1000 A) is used for the bottom cathode contact.The measured forward drop of the pn diode with AlN as the interface material is found to be around 5.1 V;whereas,it is 3 V for the other sample structure.The measured reverse-blocking voltage is found to be greater than 200 V. We report the fabrication and characterization of a vertical pn power diode which is realized using two separate epitaxial-growth mechanisms: (a) p-GaN over p- (4H) SiC, and (b) p- GaN over n- SiC with AlN as the interface layer. All of the cases, n ~ + -doped (4H) SiC serves as the cathode substrate. Pd (200 A) / Au A) is used for the bottom cathode contact. The measured forward drop of the pn diode with AlN as the interface material is found to be approximately 5.1 V; is found to be greater than 200 V.