Amorphous-to-crystalline phase transition of (lnTe)_x(GeTe) thin films

摘要

The crystallization speed (v) of the amorphous (InTe)_x(GeTe) (x=0.1, 0.3, and 0.5) films and their thermal, optical, and electrical behaviors were investigated by using a nanopulse scanner (wavelength=658 nm, laser beam diameter <2 μm), x-ray diffraction, a four-point probe, and a UV-vis-IR spectrophotometer. These results were compared to the results for a Ge_2Sb_2Te_5 (GST) film, which was comprehensively utilized for phase-change random access memory (PRAM). Both the v-value and the thermal stability of the (InTe)_(0.1)(GeTe) and (InTe)_(0.3)(GeTe) films were enhanced in comparison to the GST film. Contrarily, the v-value of the (InTe)_(0.5)(GeTe) film was so drastically deteriorated that it could not be quantitatively evaluated. This deterioration occurred because the amorphous (InTe)_(0.5)(GeTe) film had relatively high reflectance, resulting in the absorption being too low to cause the crystallization. Conclusively, proper compositional (InTe)_x(GeTe) films (e.g., x<0.3) could be good candidates for PRAM application with both high crystallization speed and thermal stability.