Effects of Ge doping on the properties of Sb2Te3 phase-change thin films

Ge-doped Sb2Te3 films were prepared by magnetron sputtering of Ge and Sb2Te3 targets on SiO2/Si (1 0 0) substrates. The effect of Ge doping on the structure was studied in details by X-ray diffraction, differential scanning calorimetry, and X-ray photoelectron spectroscopy measurements. It is indicated that Ge atoms substitute for Sb/Te in lattice sites and form Ge-Te bonds, moreover, a metastable phase was observed in Ge-doped specimens. Both crystallization temperature and resistivity of amorphous Sb2Te3 increase after Ge doping, which are beneficial for improving room temperature stability of the amorphous state and reducing the SET current of chalcogenide random access memory.