Reducing structural change in the phase transition of Ge-doped Bi0.5Sb1.5Te3 to enable high-speed and low-energy memory switching

The improving efficiency in obtaining renewable energy has promoted the deployment of electronic systems in the area of limited wired power-supply, whereas the use of devices with reduced threshold-voltage and power-consumption is essential for guaranteeing continuous working capability. Herein, Bi0.5Sb1.5Te3 was optimized by introducing Ge for high-speed and low-energy phase change memory (PCM) application. The high speed of 10 ns and the low threshold voltage of 1.6 V have been achieved, originating from the crystal-like octahedral motifs in the amorphous phase, in which crystallization can be accomplished by the shifting or rotation of these motifs. The good endurance of 10(5) cycles is due to the small volume change of 4.6% and the formation of a homogenous phase during crystallization, which reduces the risk of stress- and segregation-induced device failure. The nucleation-dominated crystallization behavior of Ge1.3Bi0.5Sb1.5Te3 is observed, where the Ge atoms with lowest electronegativity are preferred to occupy the center cation layers in the nonuple-layer block, whereas the less metallic Bi and Sb atoms sit on the edged cation layers. The high-speed, low threshold voltage, and low power consumption have made the Ge1.3Bi0.5Sb1.5Te3 PCM film a promising candidate for application in self-powered electronic systems, i.e. Internet of Things systems with solar energy supply.