Characterization of GaN/(4H)SiC Heterostructure Vertical pn Power Diode

In this work, we report the characterization results of the fabricated GaN/(4H)SiC heterostructure vertical pn power diode. The diode is realized using four separate epitaxial growth mechanisms: (a) direct growth of p-GaN over n-(4H)SiC; (b) growth of p-GaN over n-(4H)SiC with AlN as the interface layer; (c) growth of p-GaN over n-(4H)SiC with Ga-flux as the interface layer; and (d) growth of p-GaN over p-(4H)SiC. In all of these four samples, n ⁺-doped (4H)SiC acts as the cathode substrate. For all of the four cases, the metallization for the anode contact is Pd(200 A⁰)/Au(10000 A⁰) while Ni(1000 A⁰) is used for the cathode contact. The measured forward drop of the^pn diode with AlN as the interface layer is found to be around 5.1 V whereas it is between 2 V to 3 V for the rest of the three diode samples. The measured reverse-blocking capacity of all the four diode samples is found to be greater than 200 V.