Crystallization kinetics of amorphous Ga-Sb films extended for phase-change memory

Performance of phase-change RAM materials based on Ga-Te-Sb was found getting better with decreasing Te content in our earlier studies. We concerned much properties of Te-free, Sb-rich binary Ga-Sb, which has been known to possess extremely fast crystallization behavior. Non-isothermal crystallization kinetics of amorphous Sb-rich Ga_xSb_100-x films were investigated by using in-situ electrical resistance - temperature measurements. The activation energy (E_c) and rate factor (K_o) were evaluated from the heating rate dependency of the peak crystallization temperature using the Kissinger´s method. The kinetic exponent (n) was deduced from the differential resistance - temperature curves during crystallization using the Ozawa´s method. The crystallization temperature (T_x = 261 to 182 °C) decreased with decreasing Ga content (Ga 23 to 9 at%). The activation energy (E_c= 8.34 to 2.31 eV) and rate factor (K_o = 4.66 × 10⁸² to 2.33 × 10²⁶ min^-1) inconsistently changed at different Ga content and reached a maximum value at composition 19 at% Ga. The n value is smaller than 1.5 as Ga> 15 at%, denoting the mechanism of one-dimensional crystal growth from nuclei. GaSb films with 16~18% Ga were found to be the optimal for use in phase-change memory.