Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China
Phasechange memory is a promising candidate for next generation memory devices. The storage performance greatly depends on the structureproperty relation of the core material, chalcogenide phasechange materials (PCMs), which makes the characterization of atomic structure and defects of PCMs crucial to the development of phasechange memory. Transmission electron microscopy (TEM) is a useful techinque for the characterization of the morphology and structure of materials. However, the highenergy electron beams can cause temporary or permanent structural changes in materials. These beam effects in fact post challenges in measuring the structural details of amorphous PCMs, including the commercialized GeSbTe compounds. Here, we carried out a systematic insitu TEM study on amorphous GeSb2Te4 thin films with the focus on electron beam effects. We showed that the amorphous films crystallized quickly if they were subjected to highdensity electron beams, while by reducing the beam intensity, the amorphous phase can be sustained for longer periods. The threshold values of electron beam intensity under given irradiation time were determined quantitively, and a map displaying the relationship of beam intensity and irradiation time was provided. Our work suggests a safe range for TEM investigations of structural details of amorphous GeSbTe materials.