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Proceedings Paper

Sub-wavelength plasmonic-enhanced phase-change memory
Author(s): Emanuele Gemo; Santiago García-Cuevas Carrillo; Joaquin Faneca; Carlota Ruíz de Galarreta; Hasan Hayat; Nathan Youngblood; A. Baldycheva; Wolfram H. P. Pernice; Harish Bhaskaran; C. David Wright
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Paper Abstract

The Ge2Sb2Te5 phase-change alloy (GST) is known for its dramatic complex refractive index (and electrical) contrast between its amorphous and crystalline phases. Switching between such phases is also non-volatile and can be achieved on the nanosecond timescale. The combination of GST with the widespread SiN integrated optical waveguide platform led to the proposal of the all-optical integrated phase-change memory, which exploits the interaction of the guided mode evanescent field with a thin layer of GST on the waveguide top surface. The relative simplicity of the architecture allows for its flexible application for data storage, logic gating, arithmetic and neuromorphic computing. Read operation relies on the transmitted signal optical attenuation, due to the GST extinction coefficient. Write/erase operations are performed via the same optical path, with a higher power ad-hoc pulsing scheme, which locally increases the temperature and triggers either the melt-quench process (write) or recrystallization (erase), encoding the information into the GST crystal fraction. Here we investigate the physical mechanisms involved in the write/erase and read processes via computational methods, with the view to explore novel architecture concepts that improve memory speed, energy efficiency and density. We show the achievements of the development of a 3D simulation framework, performing self-consistent calculations for wavepropagation, heat diffusion and phase-transition processes. We illustrate a viable memory optimization route, which adopts sub-wavelength plasmonic dimer nanoantenna structures to harvest the optical energy and maximize light-matter interaction. We calculate both a speed and energy efficiency improvement of around one order of magnitude, with respect to the conventional (non-plasmonic) device architecture.

Paper Details

Date Published: 26 February 2020
PDF: 11 pages
Proc. SPIE 11289, Photonic and Phononic Properties of Engineered Nanostructures X, 112891E (26 February 2020); doi: 10.1117/12.2546031
Show Author Affiliations
Emanuele Gemo, Univ. of Exeter (United Kingdom)
Santiago García-Cuevas Carrillo, Univ. of Exeter (United Kingdom)
Joaquin Faneca, Univ. of Exeter (United Kingdom)
Carlota Ruíz de Galarreta, Univ. of Exeter (United Kingdom)
Hasan Hayat, Univ. of Exeter (United Kingdom)
Swansea Univ. (United Kingdom)
Nathan Youngblood, Univ. of Oxford (United Kingdom)
A. Baldycheva, Univ. of Exeter (United Kingdom)
Wolfram H. P. Pernice, Univ. of Muenster (Germany)
Harish Bhaskaran, Univ. of Oxford (United Kingdom)
C. David Wright, Univ. of Exeter (United Kingdom)

Published in SPIE Proceedings Vol. 11289:
Photonic and Phononic Properties of Engineered Nanostructures X
Ali Adibi; Shawn-Yu Lin; Axel Scherer, Editor(s)

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