Formation of Ge[sub 2]Sb[sub 2]Te[sub 5]–TiO[sub x] Nanostructures for Phase Change Random Access Memory Applications

Abstract

Amorphous Ge 2 Sb 2 Te 5 clusters with a size of 20 nm, self-enclosed by a thin layer of TiO x , were obtained by cosputtering Ge 2 Sb 2 Te 5 and TiO 2 targets at room temperature with the aim of reducing the reset current for phase change random access memory applications. Eutectic decomposition during the deposition caused a phase separation of Ge 2 Sb 2 Te 5 and TiO x . The temperature-dependent resistance change results showed that the activation energy for crystallization increased from 2.44 Ϯ 0.76 to 3.84 Ϯ 1.43 eV in the Ge 2 Sb 2 Te 5 film. The set resistance can be tuned within an acceptable range, and the reliability of this microstructure during repetitive laser melt-quenching cycles was tested.

Evaluating Broader Impacts of Nanoscale Thermal Transport Research

“…The PCM research community has leveraged and extended the TDTR and 3ω methodologies to reveal a variety of the fascinating thermal transport phenomena that occur in the phase-change chalcogenides [114][115][116][117][118][119][120][121][122][123][124][125][126][127][128][129][130]. The TDTR methodology has proven useful for extracting coupled (and even decoupling [125]) film and interface properties.…”

“…(b) Schematic illustration of the programming pulses, which require extreme temperature transients, which involve complex electrothermal phenomena. (c) Room-temperature thermal conductivity data for Ge 2 Sb 2 Te 5 films [114][115][116][117][118][119][120][121][122][123][124][125][126][127][128][129][130]. The circles are obtained from the 3ω measurements [114, 115, 119-121, 126, 127] and the diamonds are obtained from the TDTR measurements [116-118, 122-125, 128-130].…”

Interface-controlled thermal transport properties in nano-clustered phase change materials

“…Among such approaches, one of the successful methods is to induce the spontaneous formation of nano-clusters by mixing stable oxide materials, such as TiO x (Ref. 9) or SiO x (Ref. 10), into the phase change material, Ge 2 Sb 2 Te 5 (GST).…”

Controllable crystal growth and fast reversible crystallization-to-amorphization in Sb2Te-TiO2 films

“…TiO x is more stable in thermodynamic and less resistive in electric than SiO x 22, which can lower the threshold voltage and power consumption in a memory device based on GST-TiO x phase-change layer22. As a favored doping element, it is surprising that there are few reports of doping TiO 2 into Sb 2 Te for memory applications, and the phase-change kinetics in terms of the fundamental nucleation and growth theories are ambiguous.…”