Electrical and optical properties of nickel-doped Ge2Sb2Te5 films produced by magnetron co-sputtering

Pengfei Guo; Gary A. Sevison; Joshua A. Burrow; Imad Agha; Andrew Sarangan

doi:10.1117/12.2320843

19 September 2018 Electrical and optical properties of nickel-doped Ge₂Sb₂Te₅ films produced by magnetron co-sputtering

Pengfei Guo, Gary A. Sevison, Joshua A. Burrow, Imad Agha, Andrew Sarangan

Proceedings Volume 10730, Nanoengineering: Fabrication, Properties, Optics, and Devices XV; 107300L (2018) https://doi.org/10.1117/12.2320843
Event: SPIE Nanoscience + Engineering, 2018, San Diego, California, United States

Abstract

A magnetron co-sputtering system was used for producing nickel-doped Ge₂Sb₂Te₅ (GST-Ni) thin films. The nickel content in the thin film was adjusted by the ratio of the plasma discharge power applied to the GST and nickel targets, as well as a physical shuttering technique to further control the nickel deposition rate. The doping concentration of the film was confirmed using Energy Dispersion Spectroscopy (EDS) technique. Results from a four-point probe measurement indicate that the nickel doping can reduce the resistivity of GST in the amorphous state by nearly three orders of magnitude. The dopant’s influence on crystallization behavior was studied by analyzing X-Ray Diffraction (XRD) patterns of the pure GST and GST-Ni at different annealing temperatures. To examine the structural changes due to the nickel dopant, the thin films were investigated with the aid of Raman scattering. Additionally, we extracted the optical constants for both the amorphous and crystalline states of undoped-GST and GST-Ni films by ellipsometry. The results indicate that at low doping concentrations nickel does not appreciably affect the optical constants, but dramatically improves the electrical conductivity. Therefore, nickel-doping of GST a viable method for designing optical devices for lower operating voltages at higher switching speeds.

Conference Presentation

Citation Download Citation

Pengfei Guo, Gary A. Sevison, Joshua A. Burrow, Imad Agha, and Andrew Sarangan "Electrical and optical properties of nickel-doped Ge₂Sb₂Te₅ films produced by magnetron co-sputtering", Proc. SPIE 10730, Nanoengineering: Fabrication, Properties, Optics, and Devices XV, 107300L (19 September 2018); https://doi.org/10.1117/12.2320843

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