Assisted cubic to hexagonal phase transition in GeSbTe thin films on silicon nitride

The amorphous to face-centered cubic (fcc) and fcc to hexagonal close-packed (hcp) crystallization temperatures of GeSbTe thin films on underlying silicon nitride and silicon dioxide films were studied through slow (1K/min) resistance versus temperature measurements. The amorphous to fcc phase transition is observed at ~170°C for both cases but the fcc to hcp phase transition temperature for GeSbTe films on silicon nitride is observed to be ~80°C lower than for GeSbTe films on silicon dioxide, possibly due to the hexagonal symmetry of silicon nitride.