Thermal stability and crystallization speed of Cu-doped Ge8Sb2Te11 thin films

摘要

The objective of this study was to evaluate structural and electrical properties of Cu-doped Ge8Sb2Te11 thin films. Thermal stability and crystallization speed in nanosecond time scale of these of Cu-doped Ge8Sb2Te11 thin films prepared by a radio frequency (RF) magnetron reactive sputtering were also determined. A one-step phase transformation from an amorphous phase to a face-centered-cubic (fcc) phase and an increase of crystallization temperature (T-c) were observed for the Cu-doped film, indicating an enhanced thermal stability in the amorphous state. The sheet resistance (R-s) of the amorphous phase in the Cu-doped film was about 1.5 orders of magnitude larger than that in undoped film. The larger R-s, in the amorphous phase will reduce the programming current in the memory device. An increase of threshold voltage (V-th) was seen in the Cu-doped thin film, implying a high thermal efficiency. The SET voltage of the Cu-doped film was improved with an increase of the pulse voltage. The SET speed of the Cu-doped thin film was about 30 ns, suggesting that such thin film could be a good candidate for the fast crystallization PRAM.