Amorphous-to-crystalline phase transition of $(InTe)x(GeTe)$ thin films

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 (⁠$wavelength=658nm$⁠, laser beam diameter $<2μm$⁠), x-ray diffraction, a four-point probe, and a UV-vis-IR spectrophotometer. These results were compared to the results for a $Ge2Sb2Te5$ (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.