Plasma and Annealing Treatments to Form Height-Barrier Ni-Based Schottky Contact to n-GaN

We investigated the combined effects of plasma and annealing treatments on the electrical and interfacial reactions of Ni/Au Schottky contacts on n-GaN for high-efficiency electronic and optoelectronic devices. Thermionic emission (TE)-based ideal current-voltage model showed that the Schottky barrier heights (SBHs) ranged from 0.68 to 0.92 eV and the ideality factors were in the range of 1.16-2.15. On the other hand, inhomogeneity model and capacitance-voltage characteristics gave similar SBHs in the range of 1.11-1.45 eV. X-ray photoemission spectroscopy (XPS) results displayed that annealing caused the Ga 2p core level to shift toward lower energies by 0.17-0.18 eV, while plasma treatment induced the Ga 2p core level to shift toward higher energies by 0.12 eV. The XPS Ni 2p core level results exhibited that annealing samples at 600 degrees C gave rise to the formation of NiO and Ni2O3 in addition to Ni3Ga4 and Ni3Ga interfacial phases, which were confirmed by X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM) results. Based on the XPS, XRD, and STEM results, the annealing and plasma-treatment-induced increase in the SBHs is described and discussed. (C) 2019 The Electrochemical Society.