Simultaneously introducing tetrahedral and pseudo-octahedron by single-element doping enables faster and more stable phase change memory

Abstract

Phase change memory (PCM) is one of the most promising candidates for the next generation non-volatile memory, but how to balance the contradiction between thermal stability and speed remains the bottleneck problem that limit its application as a universal memory. Here, we innovatively introducing the tetrahedral cluster and the pseudo-octahedron composed of fourfold abab rings at the same time into Sb2Te3 amorphous matrix by elemental Cu doping. The increased Cu tetrahedral clusters bring about enhanced amorphous stability in Sb2Te3 and raise its crystallization temperature from 153.3 ℃ to 203.7 ℃. Besides, the reduced number of the lone-pair electrons, the stronger bond strength and the greater Peierls-like distortions also play crucial roles. Simultaneously, crystallization process simulation results show the fourfold abab ring structure, as a crystalline precursor, accelerates the crystallization speed remarkably. Experimentally, 14 ns SET speed is achieved in Cu0.2(Sb2Te3)0.8 based PCM device, which is four times faster than in pure Sb2Te3 device. Therefore, by a simple single-element doping process, both amorphous stability and crystallization speed are improved at the same time.