Carbon-doped Sb-rich Ge-Sb-Te (Sb-CGST) is proved to be a promising candidate for phase change memory because of it high crystallization temperature (higher than 200°C) and 10-year data retention temperature (higher than 120°C). The carbon-doped Sb-rich Ge-Sb-Te (Sb-CGST) films were deposited on SiO2/Si (100) substrate by RF magnetron co-sputtering using CGST alloy target (a GST target containing 16 at. % C) and Sb targets at room temperature. The content of Sb in the films was controlled by adjusting the sputtering power ratio of CGST and Sb. The results showed that both of these two properties increase firstly and then decreases with increasing the content of Sb, which are superior to that of Ge2Sb2Te5. Furthermore, Sb-CGST based PCM cells were fabricated to investigate the property of material. 6ns pulse could realize SET operation, and 3.2 x 10-11J energy can realize RESET operation.

Power consumption has long been a great obstacle in phase change memory technology. Silicon carbide was introduced to be a buffer layer between the phase change material and the metal electrode in this work. The results showed that the new structure mitigated the energy consumption and maintained the advantage of high speed. This is attributed to the thin SiC buffer layer that helps confine the generated Joule heat inside the active phase change volume and form more conducting paths by the high efficiency of the heat utilization. Additionally, another key role — inhibition of the material separation, is conducive to achieving stable and sustainable electrical operations.

In the past 20 years, the phase-change memory technology has achieved rapid development, of which alloys along the GeTe-Sb2Te3 pseudobinary line are the most extensively researched materials. In recent years, Sb2Te3-based materials start to attract the attention of researchers. A recent study has shown that the Sb2Te3 (ST) material has a face-centered cubic (Fcc) phase which contains a high concentration of vacancies at low temperature. Due to the poor amorphous thermal stability of ST, the as-deposited film obtained by physical vapor deposition is crystalline (Fcc phase). Therefore, we proposed a vacancy control mechanism, using inert gas Ar to ion implantation of as-deposited ST films, redistributing vacancies in the as-deposited ST films. Through different doses of Ar ion implantation, we obtain amorphous ST materials with different resistivity. We find that after the injection dose reached 1 × 1016 cm-2, the effect of continued increase in the implantation dose on the resistivity of the thin film is negligible. After ion implantation, the transition temperature of the metastable Fcc phase to the hexagonal phase (Hex) is increased, which is beneficial to improve the power consumption and endurance of the device. The ST which is injected with a dose of 1 × 1016 cm−2 Ar ion based phase-change memory cell can perform erasing operation in 100 ns, showing low power consumption potential. Our work provides a new idea and method for the application of future defect control in phase-change memory research.

Electron beam (EB) annealing was used to acquire a reasonable and stable component in Si-Sb-Te material. For Si2Sb2Te5phase change material, EB irradiation can induce phase separation and some regions have remained unchanged, which manifests as SixSb2Te3. The component of these steady areas was considered as reasonable in which Sb2Te3is a stable compound. The crystallized Si3.3Sb2Te3film after EB irradiation exhibited nanoscale grains with well-proportioned distribution and these grains were all with Sb2Te3structure surrounded by amorphous. This unique structure brings fast phase change speed which is at least 12 times more rapidly than Si2Sb2Te5material because it localizes atoms’ diffusion in a nanoarea during reversible phase transition process.

Ni-doped Ge-Te (Ni-GT) material was proposed and investigated for phase change random access memory (PCRAM) applications. With Ni addition, the crystallization temperature, data retention ability and crystallization speed were obviously improved. The surface roughness of crystalline Ni-GT films was decreased by Ni incorporation. Moreover, temperature dependent transmission electron microscopy (TEM) was applied to investigate the phase change behavior of Ni-GT films. All the experimental results demonstrated that Ni-GT material has potential for high-speed PCRAM applications in high temperature environment.