Quantum size effects in GaAs nanodisks fabricated using a combination of the bio-template technique and neutral beam etching

Abstract

We successfully fabricated defect-free, distributed and sub-20-nm GaAs quantum dots (named GaAs nanodisks (NDs)) by using a novel top-down technique that combines a new bio-template (PEGylated ferritin) and defect-free neutral beam etching (NBE). Greater flexibility was achieved when engineering the quantum levels of ND structures resulted in greater flexibility than that for a conventional quantum dot structure because structures enabled independent control of thickness and diameter parameters. The ND height was controlled by adjusting the deposition thickness, while the ND diameter was controlled by adjusting the hydrogen-radical treatment conditions prior to NBE. Photoluminescence emission due to carrier recombination between the ground states of GaAs NDs was observed, which showed that the emission energy shift depended on the ND diameters. Quantum level engineering due to both diameter and thickness was verified from the good agreement between the PL emission energy and the calculated quantum confinement energy.

Electron g-factor and spin decoherence in GaAs quantum nanodisks fabricated by fully top-down lithography

“…The GaAs NDs were prepared in a manner similar to that described in [3,4]. First, three layers of an 8-nm-thick GaAs/Al 0.15 Ga 0.85 As QW were sandwiched by 100-nm-thick Al 0.15 Ga 0.85 As barrier layers and a 1.4-μm-thick Al 0.30 Ga 0.70 As bottom cladding layer was grown on a GaAs (100) substrate by metal-organic vapor phase epitaxy (MOVPE).…”

“…Quantum nanodisks (NDs) of GaAs with desirable optical qualities have recently been grown from quantum wells (QWs) by fully top-down lithography, using damage-free neutral-beam etching aided by bioengineering [1][2][3][4]. This fabrication method allows us to flexibly design the structural parameters of the NDs.…”

“…This fabrication method allows us to flexibly design the structural parameters of the NDs. Specifically, the thickness, diameter, and interval can be individually controlled by protein engineering [3,4]. This enables us to investigate effects of the lateral quantum confinement of carriers or excitons on spin dynamics.…”

Impact of artificial lateral quantum confinement on exciton-spin relaxation in a two-dimensional GaAs electronic system

“…[16][17][18] These NDs were directly fabricated from GaAs QWs by newly developed top-down lithography using ultra-low-damage neutral-beam etching 19 aided by protein-engineered bio-nano-templates of ferritin supramolecules. 20 These unique NDs provide us with the first good opportunity for quantitative testing of the effects of strong lateral quantum confinement on spinrelaxation dynamics.…”

“…Details of the preparation of GaAs ND samples have been provided elsewhere. 16,17 First, doublelayered QWs of GaAs/Al 0.15 Ga 0.85 As with GaAs-well thicknesses of 8 and 4 nm were grown on GaAs (100) substrates using metal-organic vapor phase epitaxy (MOVPE). The surface was coated with ferritin supramolecules containing iron nanoparticles in their cavities.…”