Laser Synthesis of Sn-Ge-Sb-Te Phase Change Materials

Sn-doped Ge-Sb-Te films on Si substrates were prepared by laser synthesis at the different growth temperatures. The compositions of Sn-doped Ge-Sb-Te films were analysized by X-ray photoelectron spectroscopy. The crystal structures of Sn-doped Ge-Sb-Te thin films with a Sn content of less than 30 at% are close to Ge2Sb2Te5. The crystallization behaviors of Sn-doped Ge-Sb-Te films were analyzed by self-developed phase change temperature tester. The crystallization temperatures of Sn4.3Ge32.9Sb28.1Te34.6, Sn9.8Ge20.3Sb28.4Te41.5 and Sn18.8Ge19.5Sb25.3Te36.4 are 141.5, 137.3 and 135.0 °C at a ramp rate of 20 °C/min, respectively. Doping Sn into Ge-Sb-Te will result in a decrease of crystallization temperature. It was also found that crystallization temperature increases with an increase of ramp rate for a phase change material. The activity energy Ea and frequency factor ¦O for Sn9.8Ge20.3Sb28.4Te41.5 thin films are 2.42 eV and 1.7 × 1026 Hz, respectively. The crystallization speed of Sn-doped Ge-Sb-Te is estimated to be faster than Ge2Sb2Te5.