Physical and chemical characterization of laser-recorded phase-change marks on amorphous ge₂sb₂te₅ thin films

As-deposited thin films of Ge₂Sb₂Te₅ are investigated for the purpose of understanding the local electrical conductivity and structural phase-transitions of recorded marks under the influence of focused laser beam. We have written on these films micron-sized crystalline marks, ablated holes surrounded by crystalline rings, and other multi-ring structures containing both amorphous and crystalline zones with the aid of a focused laser beam. The high-contrast conductivity of GST recorded marks under various illumination conditions were investigated using Conductive-Atomic Force Microscopy (C-AFM). Also, selective chemical etching of recorded marks in conjunction with optical, atomic force, and electron microscopy as well as local electron diffraction analysis are used to discern the complex structural features created under a broad range of laser powers and pulse durations. Clarifying the nature of physical and chemical characterization associated with laser-recorded marks in chalcogenide Ge₂Sb₂Te₅ thin films provides useful information for reversible optical and electronic data storage, as well as for phase-change (thermal) lithography.