Phase Transformation Behavior of N-Doped Ge[sub 2]Sb[sub 2+x]Te[sub 5] Thin Films (x=0, 0.2) for Phase Change Memory

Abstract

and nitrogen-doped films were deposited by dc magnetron sputtering on substrates and the effects of antimony (Sb) and nitrogen (N) doping on microstructure and sheet resistance were investigated. After annealing at various temperatures between 100 and , phase transformations in and nitrogen-doped films were investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The sheet resistance of those samples was measured by four-point probe. XRD and plan-view TEM analysis showed that the addition of Sb and N elements to pseudo-binary caused crystallization and phase transformation from face-centered cubic (fcc) structure to hexagonal close-packed (hcp) structure to occur at higher temperatures with grain refinement. Also, the Sb and N doping produces increased sheet resistance in films with improved phase stability of amorphous and fcc structures up to higher temperatures. N-doped with high sheet resistance is favored for phase-change random access memory application because of reduced writing current with increased crystallization speed and thermal stability.