Preparation and observation of an artifact-free Ge2Sb2Te5 TEM specimen by the small angle cleavage technique

The amorphous Ge2Sb2Te5 thin film for the application to the non-volatile memory device was prepared by the pulsed laser deposition on a SiO2/Si substrate. The amorphous Ge2Sb2Te5 which has the TC around 150°C is readily crystallized when exposed to a comparable heat such as the Ar beam irradiation during the conventional ion milling process. Retaining its amorphous initial phase is important in order to precisely observe and understand the crystallization behaviour whether it be the sample for a pure materialistic research or applied into the device. To avoid such deterioration of the film’s amorphous nature, the complete mechanical TEM specimen preparation which is called the small angle cleavage technique (SACT) was adopted to show thermally undisturbed, an artifact-free amorphous Ge2Sb2Te5 TEM specimen. The two distinctive amorphous and crystalline phases has been observed by the HRTEM study.