| AVS 59th Annual International Symposium and Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS2-ThM |
| Session: | Low Damage Processing |
| Presenter: | Y. Tamura, Tohoku University, Japan |
| Authors: | Y. Tamura, Tohoku University, Japan M. Igarashi, Tohoku University, Japan M.E. Fauzi, Tohoku University, Japan W. Hu, Tohoku University, Japan I. Yamashita, Nara Institute of Science and Technology, Japan S. Samukawa, Tohoku University, Japan |
| Correspondent: | Click to Email |
The III-V compound quantum dot (QD) has recently become extremely attractive when researching the quantum effect and developing novel opt/electronic devices such as high-efficiency intermediate-band solar cells. In the latter one, it is very important to precisely control the geometry size and alignment of QDs to form an intermediate-band. A high in-plane density is also necessary for photovoltaic devices in order to obtain a large optical gain. Molecular beam epitaxy have widely used and have been greatly researched for forming QDs. However, it is still a great challenge for realizing ideal nanostructures using self-organized bottom-up processes.
Our proposed top-down process of using bio-template [1] and neutral beam etching (NBE) [2] has great potential to fabricate defect-free, high-density (more than 7×1011 cm-2), sub-20-nm-in-diameter GaAs QDs structures [3]. This process uses 7-nm-in-diameter iron cores of ferritin (protein included iron core) as the etching mask and damage-free NB with eliminating UV photons and high-energy ions to etch GaAs without defects.
In this study, we successfully fabricated high aspect ratio nano-pillars etched the GaAs/AlGaAs stack-layered structure with 95 nm height and 15 nm the diameter by using a NBE. The diameter of the GaAs nanodisk could be precisely controlled from 12 to 18 nm by a combination of Hydrogen-radical treatment and Cl2-NBE. This is because a taper profile of GaAs-NBO film could be controlled by Hydrogen-radical treatment time due to the isotropic and slow etching rate. In addition, not only iron cores but also this tapered GaAs-NBO film can work as etching masks because of the high NBE selectivity of GaAs-NBO. Thus, the diameter of the GaAs nanodisk could be controlled using the surface GaAs-NBO film taper profile produced by the prior Hydrogen-radical treatment time before NBE. This result means that our fabricated nanodisk array structures have great potential for high performance III-V compound optical QDs devices.
[1] I. Yamashita. Thin Solid Films. 393. 12. (2001).
[2] S. Samukawa. Jpn. J. Appl. Phys. 45. 2395. (2006).
[3] X. Y. Wang, et al., Nanotechnology, 22. 365301. (2011).