Example embodiments presented herein are directed towards an x-ray generating device. The device comprises at least one electron emitter(s) (22, 22_1, 22_2, 22_3) which has an electrically conductive substrate (23). The electrically conductive substrate comprises a coating of nanostructures (24). The device further comprises a heating element (21) attachable to each electrically conductive substrate. The device further comprises an electron receiving component (14) configured to receiving electrons emitted from the at least one electron emitter(s). The device also comprises an evacuated enclosure (10) configured to house the at least one electron emitter(s), the heating element and the electron receiving component. The at least one electron emitter(s) is configured for Schottky emission when the heating element is in an on-state and the at least one electron emitter(s) is negatively biased.