Title
Indium Tin Oxide optical access for magnetic tunnel junctions in hybrid spintronic-photonic circuits
Date Issued
16 October 2020
Access level
open access
Resource Type
journal article
Author(s)
Olivier A.
Chavent A.
lvaro-Goémez L.
Rubio-Roy M.
Auffret S.
Vila L.
Dieny B.
Sousa R.C.
Prejbeanu I.L.
Univ. Grenoble Alpes
Publisher(s)
IOP Publishing Ltd
Abstract
The all-optical magnetization reversal of magnetic layers, by picosecond optical pulses, is of particular interest as it shows the potential for energy-efficient and fast magnetic tunnel junction (MTJ) elements. This approach requires memory elements that are optically and electronically accessible, for optical writing and electronic read-out. In this paper, we propose the integration of indium tin oxide (ITO) as a transparent conducting electrode for magnetic tunnel junctions in integrated spintronic-photonic circuits. To provide light with sufficient energy to the MTJ free layer and allow electrical read-out of the MTJ state, we successfully integrated indium tin oxide as a top transparent electrode. The study shows that ITO film deposition by physical vapor deposition with conditions such as high source power and low O2 flow achieves smooth and conductive thin films. Increase in grain size was associated with low resistivity. Deposition of 150 nm ITO at 300 W, O2 flow of 1 sccm and 8.10-3 mbar vacuum pressure results in 4.8 10-4 Ω.cm resistivity and up to 80% transmittance at 800 nm wavelength. The patterning of ITO using CH4/H2 chemistry in a reactive ion etch process was investigated showing almost vertical sidewalls for diameters down to 50 nm. The ITO based process flow was compared to a standard magnetic tunnel junctions fabrication process flow based on Ta hard mask. Electrical measurements validate that the proposed process based on ITO results in properties equivalent to the standard process. We also show electrical results of magnetic tunnel junctions having all-optical switching top electrode fabricated with ITO for optical access. The developed ITO process flow shows very promising initial results and provides a way to fabricate these new devices to integrate all-optical switching magnetic tunnel junctions with electronic and photonic elements.
Volume
31
Issue
42
Language
English
OCDE Knowledge area
Nano-tecnología Ingeniería eléctrica, Ingeniería electrónica Óptica Ingeniería de materiales
Publication version
Version of Record
Scopus EID
2-s2.0-85091650266
Source
Nanotechnology
ISSN of the container
0957-4484
Sponsor(s)
We thank Dr T. Chevolleau, T. Charvolin, C. Gomez and G. Gay for their help on the deposition and patterning of ITO. This research has received funding from the European Union s Horizon 2020 research and innovation program under FETOpen Grant Agreement No. 713481 (SPICE).
Sources of information: Directorio de Producción Científica Scopus