Abstract Influence of dislocations on diamond Schottky barrier diode characteristics of vertical structure p- layer/p+ substrate is studied. Devices are intentionally fabricated at locations corresponding to specific dislocations, stacking faults and growth sector boundaries observed using X-ray topography (XRT) prior to device fabrication. Devices fabricated on [001] threading dislocation area, and threading dislocation with stacking fault (SF) areas showed very large leakage current compared with devices without dislocations. Dislocation vectors of four devices having threading dislocations with SFs, are analyzed using XRT images and compared with current to voltage (I–V) characteristics. The number of threading dislocations and their types vary significantly, and there is not much difference in the I–V characteristics. Thus, threading dislocations are fatal to the device characteristics regardless of their dislocation directions, types, and number counts.