Enhanced performance of phase change memory by grain size reduction

Phase change materials allow non-volatile, fast-speed storage-class memory. However, thermal stability and reliability are the key challenges that limit their extensive applications, especially high-temperature applications. Here, we demonstrate an alloying strategy through alloying Ta into Ge2Sb2Te5 (GST), which presents robust data retention at 167 degrees C for 10 years, power consumption as low as one order of magnitude, and ten times longer endurance as compared with a GST-based device. The mechanism of the microstructure evolution of Ta alloying is clarified by using advanced electron microscopy and a theoretical method. The formation of strong Ta-Te coordinate bonds increases the rigidity of amorphous atomic matrices. In the grain, partial Ta is separated at the grain boundary, and inner-grain Ta atoms immensely increase cationic migration energy barriers to stabilize the metastable cubic phase. Subsequently, the inner-grain Ta atoms slowly aggregate at the grain boundary under the action of an electric field. Thus, grain growth and elemental segregation are further inhibited, effectively improving the reliability of the device. The superior thermal stability and reliability of Ta-GST devices pave the way for their widespread applications in automotive electronics and aerospace.