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Utilization of Plasmonic and Photonic Crystal Nanostructures for Enhanced Micro- and Nanoparticle Manipulation
Published on: September 27, 2011
Controlling localized surface plasmon resonances in GeTe nanoparticles using an amorphous-to-crystalline phase
Mark J Polking1, Prashant K Jain, Yehonadav Bekenstein
1Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA.
Physical Review Letters
|August 6, 2013
Summary
Crystalline germanium telluride (GeTe) nanoparticles exhibit localized surface plasmon resonance (LSPR), unlike their amorphous counterparts. Crystallization enables this plasmonic behavior by altering electronic band structure and increasing free carrier density.
Area of Science:
- Materials Science
- Nanotechnology
- Condensed Matter Physics
Background:
- Germanium telluride (GeTe) is a phase-change material with distinct amorphous and crystalline structures.
- Understanding the optical properties of GeTe nanoparticles is crucial for applications in plasmonics and optoelectronics.
Purpose of the Study:
- To investigate the difference in plasmonic properties between amorphous and crystalline GeTe nanoparticles.
- To elucidate the underlying electronic mechanisms responsible for the observed optical behavior.
Main Methods:
- Infrared absorption spectroscopy was used to measure the optical response of GeTe nanoparticles.
- Scanning tunneling spectroscopy (STS) was employed to probe the electronic density of states.
Main Results:
- A localized surface plasmon resonance (LSPR) mode was observed in crystalline GeTe nanoparticles, but not in amorphous ones.
- Crystallization of amorphous GeTe nanoparticles led to the emergence of the LSPR mode.
- STS revealed a Burstein-Moss shift in the band gap of crystalline GeTe, indicating higher free carrier density, while amorphous GeTe showed states within the band gap, limiting free carriers.
Conclusions:
- The presence of LSPR in crystalline GeTe nanoparticles is attributed to their distinct electronic band structure and higher free carrier density.
- Amorphous GeTe nanoparticles lack LSPR due to a limited effective free carrier density caused by electronic states within the band gap.
- Controlling the phase of GeTe nanoparticles is key to tuning their plasmonic properties.
