Enhanced reliability of phase-change memory via modulation of local structure and chemical bonding by incorporating carbon in Ge₂Sb₂Te₅

Abstract

Charge density differences (CDDs) on Ge–C–Sb bonds in CGST(5%) and Ge–C–Sb in CGST(10%).

Enabling Active Nanotechnologies by Phase Transition: From Electronics, Photonics to Thermotics

“…The main reason for the smaller drift coefficient is the reduced resistance in the amorphous state, as reported by Lacaita group . Besides, the resistance drift in the amorphous state was evaluated in C-GST (5%) and C-GST (10%) recently . With the same operating voltage, the cyclability and resistance drift performance are continuously enhanced by doping more C in GST.…”

“…Doping impurities in semiconductors is a typical technique to control carrier densities, Fermi level, and other properties, widely used in configuring PCM to enhance memory cell performances. From the early 2000s, many dopants, including C, − N, − Cu, − Ni, O, Ga, Ru, Sc, , BN, and SiC, have been used in GeSbTe or GeTe alloy with reported enhanced performance. Dopants can increase the disorder or form new types of bonds in amorphous states, leading to higher resistance and increased T c .…”

“…Additionally, other characteristics of phase transition-based memory such as resistance drift were also improved by incorporating with impurities. , The resistance drift in SET states originates from the stress release after quick quenching in the RESET process, which causes the material relaxation to lower energy state. Basically, the resistance drift is governed by a power-law relationship as ,, Here t is the time since the cell is programmed, and R ( t 0 ) is the resistance at time t 0 .…”

“…Taking advantage of the tunable thermal emissivity, different functionalities have been realized including thermal camouflage, , anticounterfeiting, radiative cooling of buildings, and much more. ,, Nevertheless, the dramatic variation of thermal properties can only happen around the phase change temperature, which hampers further applications of PCMs in a wide range of temperatures. One effective method to overcome this limitation is to alter the temperature of phase transition, for instance, through doping impurities. ,,− One notable example is doping tungsten in VO 2 to expand its applicable range of emissivity modulation . Recent advances on the W-VO 2 have been reported for a variety of functions, such as temperature-independent camouflage, thermal imaging sensitizer, as well as the radiative cooler …”

“…196 Besides, the resistance drift in the amorphous state was evaluated in C-GST (5%) and C-GST (10%) recently. 181 With the same operating voltage, the cyclability and resistance drift performance are continuously enhanced by doping more C in GST. The researchers argue that the stable resistance in RESET state roots in the generation of C−Ge chemical bonds when GST is doped with a low C concentration.…”