Temperature-Dependent Local Structural Changes of Amorphous Thin Ge20Te80Film Revealed by In Situ Resistance, X-Ray Diffraction, and Raman Spectroscopy Studies

Although numerous chalcogenide glass systems including GeTe(6)and Ge(x)Se(100-x)have been explored for Ovonic Threshold Switch (OTS) selectors in vertically stackable cross-point memory applications, yet an improved thermal and structural stability at elevated temperatures remains a key challenge. Herein, a systematic temperature-dependent experimental investigation on the thermal stability and local structural changes of as-deposited amorphous thin Ge(20)Te(80)film is conducted for a wide range of temperatures from 25 to 260 degrees C. The coherent experimental studies reveal that the amorphous phase is stable up to 180 degrees C, and the crystallization process is initiated above 180 degrees C, by simultaneous crystallization of Te and GeTe until approximate to 238 degrees C as substantiated by temperature-dependent sheet resistance, X-ray diffraction, and Raman spectroscopic measurements. Furthermore, the local structural changes over the crystallization process of Ge(20)Te(80)thin film are elucidated by Raman spectroscopy. These experimental findings provide a decisive understanding of the thermal stability and structural evolution of Ge(20)Te(80)thin films toward designing stable OTS selector materials.