Dislocation reduction in nitride-based Schottky diodes by using multiple Mg_xN_y/GaN nucleation layers

We present the characteristics of nitride-based Schottky diodes with a single low-temperature (LT) GaN nucleation layer and multiple Mg_xN_y/GaN nucleation layers. With multiple Mg_xN_y/GaN nucleation layers, it was found that reverse leakage current became smaller by six orders of magnitude than that with a conventional LT GaN nucleation layer. This result might be attributed to the significant reduction of threading dislocations (TDs) and TD-related surface states. From the double crystal X-ray diffraction and photoluminescence analyses, it was found that the introduction of multiple Mg_xN_y/GaN nucleation layers could be able to effectively reduce the edge-type TDs. Furthermore, it was also found that effective Schottky barrier height (Φ_B) increased from 1.07 to 1.15 eV with the insertion of the multiple Mg_xN_y/GaN nucleation layers.