Crystallization of Ge_2Sb_2Te_5 phase-change optical disk media
摘要
In this paper, the crystallization behaviour of amorphous Ge_2Sb_2Te_5 thin films is investigated using differential scanning calorimetry), x-ray diffraction and optical transmissivity measurements. It is indicated that only the amorphous phase to face-centred-cubic phase transformation occurs during laser annealing of the normal phase-change structure, which is a benefit for raising the phase-change optical disk's carrier-to-noise ratio (CNR). For amorphous Ge_2Sb_2Te_5 thin films, the crystallization temperature is about 200°C and the melting temperature is 546.87°C. The activation energy for the crystallization, Ea, is 2.25eV. The crystallization dynamics for Ge_2Sb_2Te_5 thin films obeys the law of nucleation and growth reaction. The sputtered Ge_2Sb_2Te_5 films were initialized by an initializer unit. The initialization conditions have a great effect on the reflectivity contrast of the Ge2Sb2Te5 phase-change optical disk.