Effects of Si doping on the structural and electrical properties of Ge2Sb2Te5 films for phase change random access memory (original) (raw)

The effects of Si doping on the structural and electrical properties of Ge 2 Sb 2 Te 5 film are studied in detail. Electrical properties and thermal stability can be improved by doping small amount of Si in the Ge 2 Sb 2 Te 5 film. The addition of Si in the Ge 2 Sb 2 Te 5 film results in the increase of both crystallization temperature and phase-transition temperature from face-centered cubic (fcc) phase to hexagonal (hex) phase, however, decreases the melting point slightly. The crystallization activation energy reaches a maximum at 4.1 at.% and then decreases with increasing dopant concentration. The electrical conduction activation energy increases with the dopant concentration, which may be attributed to the increase of strong covalent bonds in the film. The resistivity of Ge 2 Sb 2 Te 5 film shows a significant increase with Si doping. When doping 11.8 at.% of Si in the film, the resistivity after 460 8C annealing increases from 1 to 11 mV cm compared to the undoped Ge 2 Sb 2 Te 5 film. Current-voltage (I-V) characteristics show Si doping may increase the dynamic resistance, which is helpful to writing current reduction of phase-change random access memory.