Nanoscale electrical phase-change in GeSb2Te4 films with scanning probe microscopes

Abstract Nanometer-scale electrical recordings in amorphous chalcogenide films have been studied using an atomic force microscope (AFM) and a scanning tunneling microscope (STM). When electrical pulses are applied to amorphous GeSb2Te4 films through the conducting cantilevers of the AFM, depending upon the electric power, two kinds of conductive regions appear. Low-power pulses (∼1 fJ) produce medium resistance (∼10 M Ω ) marks, and high-power pulses (∼10 pJ) give low-resistance (∼1 k Ω) marks with a minimal size of ∼50 nm. X-ray diffraction patterns of the low-resistance marks show crystalline peaks, which manifest an electrical phase-change from amorphous to crystalline states. Erasures by electrical pulses are possible. Lithography in GeSb2Te4 films with a STM is also demonstrated.