| AVS 62nd International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Tuesday Sessions |
| Session NS+EN+SS-TuA |
| Session: | Nanophotonics, Plasmonics, and Energy |
| Presenter: | Cedric Thomas, Tohoku University, Japan |
| Authors: | C. Thomas, Tohoku University, Japan A. Higo, Tohoku University, Japan T. Kiba, Hokkaido University, Japan Y. Tamura, Tohoku University, Japan N. Okamoto, Nara Institute of Science and Technology, Japan I. Yamashita, Nara Institute of Science and Technology, Japan A. Murayama, Hokkaido University, Japan S. Samukawa, Tohoku University, Japan |
| Correspondent: | Click to Email |
Fabrication of quantum dots (QD) and their use for optical devices are still facing big challenges, for instance a high-density and three-dimensional array of QDs is hardly achieved. We report here the fabrication of stacked layers of GaAs QDs (called nanodisks, NDs) of less than 20 nm in diameter by a top-down approach and their optical characteristics when embedding in light emitting device.
The fabrication process consists of a bio-template [1] used to create a high density etching mask coupled to a low-damage etching process using neutral beam (NB) [2]. The bio-template is realized by a self-assembled monolayer (SAM) of proteins called ferritins (cage like proteins) of 12 nm outside diameter with a 7 nm iron oxide core. The proteins are functionalized with poly-ethylene glycol (PEG) to control the ferritin-to-ferritin distance and avoid any ND coupling after fabrication. After removing the protein shell by oxygen based treatment, a high-density (ca. 1x1011 cm-2) nano-pattern of cores is used as etching mask. The NB etching consists of an inductively couple plasma chamber separated from the process chamber by a carbon electrode with a high aspect-ratio aperture array. Therefore, the charged particles are efficiently neutralized and the UV photons from the plasma almost completely screened
Stacks of GaAs and AlGaAs layers were grown by metalorganic vapor phase epitaxy (MOVPE), with a GaAs cap layer of a few nanometer thick. SAM of ferritins was done by spin-coating. After removing protein shell by oxygen annealing in vacuum, a hydrogen radical treatment was performed to remove to remove the oxide layer. Etching was then realized by pure chlorine NB. Regrowth of AlGaAs barrier was done by MOVPE. Finally, temperature dependence of photoluminescence emission and ND light emitting diode were measured and results discussed [3].
[1] I. Yamashita et al., Biochim. Biophys. Acta 1800 (2010) 845
[2] S. Samukawa et al., Jpn. J. Appl. Phys. 40 (2001) L997
[3] A. Higo et al., Sci. Reports 5 (2015) 9371