Effects of nitrogen doping on the properties of Ge 15Sb 85 phase-change thin film

Abstract

The effects of nitrogen doping on the chemical bonding state, microstructure, electrical property and thermal stability of Ge 15Sb 85 film were investigated in detail. The doped N atoms tend to bond with Ge to form Ge 3N 4, as proved by X-ray photoelectron spectroscopy analyses. X-ray diffraction patterns showed that both undoped and N-doped Ge 15Sb 85 films crystallize into a hexagonal phase very similar to Sb. The thickness reduction upon crystallization for undoped and N-doped Ge 15Sb 85 films is less than 5%. The crystalline resistivity, crystallization temperature, and thermal stability of amorphous state all increase after nitrogen doping, while the grain size decreases. By adding 7.0 at.% N into the Ge 15Sb 85 film, the crystalline resistivity increases twelve times and the crystallization temperature increases about 50 °C. The maximum temperature for 10-year retention of amorphous Ge 15Sb 85 film is estimated to be 147 °C and that of N-doped films is even higher, which will promise better data retention of phase-change random access memory especially in the high-temperature application.