The correlation of electrical conductivity with the microstructure of Ge2Sb2Te5 thin films alloyed with Sn

Abstract

In this research, the effects of Sn alloying on structure transformation and electrical characteristics of Ge2Sb2Te5 (GST) thin films were studied. It was discovered that the SnTe phase formed in GST thin films when Sn content exceeded 26 at%, and the addition of Sn atoms expanded the lattice parameter, as a result of atomic radii difference between Ge and Sn atoms. Furthermore, temperature dependent sheet resistance measurements on the GST:Sn thin films were performed for the electrical characteristics to be studied. Sn substitution fraction of 16 at% was discovered to maximize the crystallization temperature of GST thin films. Compared to the GST thin films, crystallization temperature difference and lower amorphous resistance of the GST:Sn thin films were mainly due to lower bonding energy of Sn–Te. Moreover, the amorphous conductivity activation energies (Eσ) corresponding to different grain sizes were calculated with the Arrhenius equation. The Eσ value of GST:Sn thin films decreased significantly as the Sn content increased due to grain size effects, which appears to improve the temperature stability of conductivity of phase change memory.