Effects of Ag doping on the crystallization properties of Sb-rich GeSb thin films

Ag-doped and un-doped Sb-rich GeSb thin films were deposited by DC magnetron co-sputtering. The electrical, structural, and optical properties of the thin films phase change were investigated using 4-point probe measurement, X-ray diffraction (XRD), transmission electron microscopy (TEM), and a static tester. With increasing Ag doping content, the crystallization temperature and sheet resistance of crystalline state decreased from 325°C to 283°C and from 187.33Ω/□ to 114.62Ω/□, respectively. XRD patterns of the films showed a Sb hexagonal structure, and the calculated grain size increased from 13.9nm to 17nm as the Ag concentration increased. Grain sizes of the Ag-doped thin films were larger than the grain sizes of un-doped thin films, as determined by TEM images. A static tester verified the decreased crystallization speed and optical contrast. Un-doped GeSb crystallization took 160ns and 16at.% Ag-doped GeSb crystallization took 200ns when the laser power was 13mW. Based on a power–time-effect diagram, the 12.6at.% Ag-doped GeSb showed good thermal stability in a crystalline state.