Electrical characteristics of a variety of Schottky contacts formed with ten metal species on the a‐plane of p‐type low‐Mg‐doped GaN grown on r‐plane sapphire substrates were studied. We found that while current–voltage characteristics obtained under voltage scanning show no memory effect in samples formed on a‐plane samples on c‐plane showed a substantial memory effects. We consider that the absence of memory effect in the a‐plane p‐GaN samples is originating from a smaller density of interfacial defect than that in the c‐plane p‐GaN samples. In internal photoemission spectra, we observed two linearly increasing portions suggesting two different Schottky barriers with different heights coexisting in a contact. A potential barrier corresponding to a linear increase locating at lower photon energy typically ranged between 1.6 and 2.5 eV; and that corresponding to another linear increase locating at higher energy ranged between 0.7 and 1.7. The barrier heights showed no relevance to metal work function. The a‐plane GaN surface was found to reveal a lamellar structure with stripes along [0001] direction with a randomly oriented roughness. We thus speculate that contact barrier spatially varies according to the different crystal plane.