Characteristics of Sn-Doped Ge₂Sb₂Te₅ Films Used for Phase-Change Memory

Sn-doped Ge₂Sb₂Te₅ thin films deposited on Si(100)/SiO₂ substrates by rf magnetron sputtering are investigated by a differential scanning calorimeter, x-ray diffraction and sheet resistance measurement. The crystallization temperatures of the 3.58 at.%, 6.92 at.% and 10.04 at.% Sn-doped Ge₂Sb₂Te₅ thin films have decreases of 5.3, 6.1 and 0.9 °C, respectively, which is beneficial to reduce the switching current for the amorphous-to-crystalline phase transition. Due to Sn-doping, the sheet resistance of crystalline Ge₂Sb₂Te₅ thin films increases about 2--10 times, which may be useful to reduce the switching current for the amorphous-to-crystalline phase change. In addition, an obvious decreasing dispersibility for the sheet resistance of Sn-doped Ge₂Sb₂Te₅ thin films in the crystalline state has been observed, which can play an important role in minimizing resistance difference for the phase-change memory cell element arrays.