In this work, Schottky barrier diodes with vertical geometry were fabricated on low-defect-density homoepitaxial GaN for studying the reverse leakage mechanism of GaN-based Schottky contact. A leakage current model based on electron transmission primarily through linear defects like dislocations was suggested to explain the reverse current-voltage characteristics measured between 300 and 410 K, in which electrons from contact metal overcome the locally height-reduced Schottky barrier through thermionic-field emission. (C) 2013 Elsevier Ltd. All rights reserved.