High-performance memristors based on AlN films have been demonstrated, which exhibit ultrafast ON/OFF switching times (approximate to 85 ps for microdevices with waveguide) and relatively low switching current (approximate to 15 mu A for 50 nm devices). Physical characterizations are carried out to understand the device switching mechanism, and rationalize speed and energy performance. The formation of an Al-rich conduction channel through the AlN layer is revealed. The motion of positively charged nitrogen vacancies is likely responsible for the observed switching.