We have studied the microscopic electronic characteristics of Ni‐Au layers on Mg‐doped GaN, using electron beam induced current to measure the carrier separation associated with built‐in electric fields. Scanning electron microscopy reveals that the metal layer has a large density of Ni islands within a Au matrix. An enhancement in the charge collection current is observed at these islands, in comparison with the matrix. These observations are explained by a local reduction in the Schottky barrier at the Ni islands.