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.

We have demonstrated the fabrication of homogeneously distributed In 0.3 Ga 0.7 N/GaN quantum nanodisks (QNDs) with a high density and average diameter of 10 nm or less in 30-nm-high nanopillars. The scalable top-down nanofabrication process used biotemplates that were spincoated on an In 0.3 Ga 0.7 N/GaN single quantum well (SQW) followed by low-damage dry etching on ferritins with 7 nm diameter iron cores. The photoluminescence measurements at 70 K showed a blue shift of quantum energy of 420 meV from the In 0.3 Ga 0.7 N/GaN SQW to the QND. The internal quantum efficiency of the In 0.3 Ga 0.7 N/GaN QND was 100 times that of the SQW. A significant reduction in the quantum-confined Stark effect in the QND structure was observed, which concurred with the numerical simulation using a 3D Schrodinger equation. These results pave the way for the fabrication of large-scale III− N quantum devices using nanoprocessing, which is vital for optoelectronic communication devices.

We fabricated a photonic crystal (PC) line-defect waveguide integrated with a microelectromechanical actuator and demonstrated the optical switching operation. The device consisted of a PC line-defect waveguide fabricated in a silicon-on-insulator substrate and a polycrystalline-Si dielectric plate located above the PC waveguide. An applied voltage moved the dielectric plate towards the PC surface due to the electrostatic force. This motion increased out-of-plane scattering of the guided light through the evanescent interaction with the dielectric plate, and modulated the transmittance of the PC waveguide. With only a 5μm interaction length, an extinction ratio of ∼10dB was obtained at a wavelength of 1568nm under an applied voltage of 60V. The response time of the switching operation was approximately 1ms.

Quantum dots photonic devices based on the III–V compound semiconductor technology offer low power consumption, temperature stability, and high-speed modulation. We fabricated GaAs nanodisks (NDs) of sub-20-nm diameters by a top-down process using a biotemplate and neutral beam etching (NBE). The GaAs NDs were embedded in an AlGaAs barrier regrown by metalorganic vapor phase epitaxy (MOVPE). The temperature dependence of photoluminescence emission energies and the transient behavior were strongly affected by the quantum confinement effects of the embedded NDs. Therefore, the quantum levels of the NDs may be tuned by controlling their dimensions. We combined NBE and MOVPE in a high-throughput process compatible with industrial production systems to produce GaAs NDs with tunable optical characteristics. ND light emitting diode exhibited a narrow spectral width of 38 nm of high-intensity emission as a result of small deviation of ND sizes and superior crystallographic quality of the etched GaAs/AlGaAs layer.