Changes in electrical and structural properties of phase-change Ge-Sb-Te films by Zr addition

• The sheet resistance ratio between amorphous and crystalline states of the Zr-GST films achieves four to five orders of magnitude.
• The crystallization temperature and 10 years data-retention of the Zr-GST films increase with the Zr concentration.
• Zr-GST films are crystallized into a single phase without phase separation.
• The incorporating Zr atoms are embedded in the inner atomic-scale structure of GST.

In this paper, the effect of Zr on the phase change properties of Ge2Sb2Te5 (GST) is systemically studied for phase-change random access memory. The sheet resistance ratio between amorphous and crystalline states achieves four to five orders of magnitude. The crystalline resistance, crystallization temperature (Tc) and the 10 years data-retention of Zr-GST films increase with the Zr concentration. Zr-GST films are crystallized into a single phase without phase separation due to the Zr bonding with Sb and Te. With the increasing annealing temperature, the transformation from face-centered cubic (fcc) to hexagonal is suppressed when the Zr atomic content is higher than 6%, which is ascribed to the lack formation of the Te-Te pairs. The wide band gap of the amorphous Zr-GST films is favorable to reduce the threshold current. The incorporating Zr atoms are embedded in the inner atomic-scale structure of the GST, which contributes to performance improvement of the GST material for phase-change random access memory.