Study of Crystallization Kinetics in GeSbTeSeM (M=Cu, Co, Ni, Pb) Phase Change Materials

抄録

We obtained the experimental exothermal curves of chalcogenide alloys Ge₄₀Sb₁₀Te₄₅Se_3.5M_1.5, M=Co, Cu, Ni, Pb, and applied the Kissinger's formula to extract the activation energy Ec. Our results indicate that the activation energy E_c, increases while doping a small amount of M metals. At isothermal electrical resistivity measurement, the resistivity of the sputtered doped films decreases with time. Also the esistivitry decrease rate (dR/dt) increases with the increase of isothermal temperature. This phenomenon is due to phase transition between amorphous and crystalline states. The crystallization process in our study is interpreted successfully by Johnson-Mehl-Avrami (JMA) transformation equation, and the crystallization time τ is extracted from the JMA equation when we compared the experimental results to the equation. We find that the crystallization time for Ge₄₀Sb₁₀Te₄₅Se₅ alloy with doping M is shorter significantly than that for Ge₄₀Sb₁₀Te₄₅Se₅ alloy without doping, and it is lower than 50 ns at 730 K and near 100 ns, respectively. These results indicate that the M dope enhances crystallization process.