Chih-Chung Chang

Crystallization behaviors of an ultra-thin Ga–Sb film

Upon decreasing ultra-thin Ga16Sb84 films from 10 to 3 nm, the exponential increase in crystallization temperature and electrical resistance ratio are attributed to increased specific interface-energies and inhomogeneous interfacial strain at the interfaces. The specific interface-energies and strain also stabilize the Sb(Ga) phase and suppress phase-separation of the GaSb phase.

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 x Sb 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 Kissingers method. The kinetic exponent (n) was deduced from the differential resistance - temperature curves during crystallization using the Ozawas 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.