Improved phase-change characteristics of Si doped GeSbTe thin films used for phase change memory

The phase-change characteristics of silicon doped Ge2Sb2Te5 (Si-GST) film were investigated and compared with pure Ge2Sb2Te5 (GST) film. The results of in situ temperature dependence of the sheet resistance demonstrate that the crystalline resistivity of GST film increased by the silicon doping, but the phase transition temperature Tc was almost unchanged. The minimum on/off ratio for Si-doped GST is around 240, which is high enough to be used for device application. Both of the GST and Si-doped GST prototype memory devices can perform SET and RESET cycles. The threshold voltage Vth increased while the RESET current decreased with silicon doping. Applying the Kissinger method the activation energy for crystallization of Si-doped GST film (300 nm) is determined to be 2.30 ± 0.05 eV.