Investigation on nitrogen-doped Ge2Sb2Te5 material for phase-change memory application

Abstract

Nitrogen-doped Ge2Sb2Te5 thin film is proposed to present the feasibility for electrical phase-change memory application. The effect of nitrogen doping on the structure is studied by in situ sheet resistance measurement and X-ray diffraction method. The temperature upon crystallization from amorphous to cubic structure is increased by nitrogen addition, while the phase transformation to hexagonal phase occurs at a lower temperature compared with the nitrogen-free Ge2Sb2Te5 material. The X-ray diffraction test reveals that the grain size has been refined significantly by the incorporation of nitrogen atoms in the film. Phase-change memory device based on nitrogen incorporated Ge2Sb2Te5 material is fabricated using complementary metal oxide semiconductor technology. A complete crystallization of the phase-change cell is realized in the current–voltage sweeping process. Nitrogen-doped Ge2Sb2Te5 with higher sheet resistance in the crystalline state is favored for phase-change memory application due to the decreased reset voltage and promoted resistance ratio of the reset and set states.