Colloidal Ternary Telluride Quantum Dots for Tunable Phase Change Optics in the Visible and Near-Infrared
Abstract
A structural change between amorphous and crystalline phase provides a basis for reliable and modular photonic and electronic devices, such as nonvolatile memory, beam steerers, solid-state reflective displays, or mid-IR antennas. In this paper, we leverage the benefits of liquid-based synthesis to access phase-change memory tellurides in the form of colloidally stable quantum dots. We report a library of ternary MxGe1-xTe colloids (where M is Sn, Bi, Pb, In, Co, Ag) and then showcase the phase, composition, and size tunability for Sn-Ge-Te quantum dots. Full chemical control of Sn-Ge-Te quantum dots permits a systematic study of structural and optical properties of this phase-change nanomaterial. Specifically, we report composition dependent crystallization temperature for Sn-Ge-Te quantum dots, which is notably higher compared to bulk thin films. This gives the synergistic benefit of tailoring dopant and material dimension to combine the superior aging properties and ultrafast crystallization kinetics of bulk Sn-Ge-Te, while improving memory data retention due to nanoscale size effects. Furthermore, we discover a large reflectivity contrast between amorphous and crystalline Sn-Ge-Te thin films, exceeding 0.7 in the near-IR spectrum region. We utilize these excellent phase-change optical properties of Sn-Ge-Te quantum dots along with liquid based processability for nonvolatile multicolor images and electro-optical phase-change devices. Our colloidal approach for phase-change applications offers higher customizability of materials, simpler fabrication, and further miniaturization to the sub-10 nm phase-change devices. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000608031Publication status
publishedExternal links
Journal / series
ACS NanoVolume
Pages / Article No.
Publisher
American Chemical SocietySubject
nanoparticles; chalcogenides; amorphous structure; crystallization; reflectivity; phase-change applications; nonvolatile devicesOrganisational unit
09531 - Grange, Rachel / Grange, Rachel
03895 - Wood, Vanessa / Wood, Vanessa
09701 - Yarema, Maksym / Yarema, Maksym
Funding
852751 - Solution-Based Engineering of Nanodimensional Phase-Change Materials and Memory Devices (EC)
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