First principle and electrical simulation with characterization of GaN/(4H)SiC heterostructure vertical PN power diode

In this work, we report the characterization results of GaN/4H-SiC heterojunction 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. The use of less than 2 nm AlN, as the interface material in one of the growth mechanisms is guided from the first principle atomistic simulation study. 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 material 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 capability of all the four diode samples is found to be greater than 200 V.