Electrical Characteristics of Thermally Stable Ag–Pd–Cu Alloy Schottky Contacts on n- Al _0.6 Ga _0.4 N

We report the fabrication of high-barrier-height and thermally reliable Schottky contacts to n- Al _0.6 Ga _0.4 N by using an Ag-Pd-Cu (APC) alloy. The Schottky barrier heights (SBHs) and ideality factors computed using the current-voltage ( I–V ) model ranged from 0.82 to 0.97 eV and from 3.15 to 3.44, respectively. The barrier inhomogeneity model and capacitance-voltage ( C–V ) method yielded higher SBHs (1.62–2.19 eV) than those obtained using the I–V model. The 300 °C-annealed APC sample exhibited more uniform electrical characteristics than the 500 °C-annealed Ni/Au Schottky samples (each with the best Schottky behavior). Furthermore, the scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) results indicated that the APC Schottky contacts were more thermally stable than the Ni/Au contacts. On the basis of the X-ray photoemission spectroscopy (XPS) results, the improved Schottky characteristics of the APC alloy contacts are described and discussed.