Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants |
|Research Institution||Osaka University |
GAMO Kenji Osaka University, Faculty of Engineering Science, Professor, 基礎工学部, 教授 (70029445)
JONES G.a. c. Univ. of Cambridge, Cavendish Lab., キャベンディッシュ研究所, 副ディレクター
AHMED H ケンブリッジ大学, キャベンディッシュ研究所・マイクロエレクトロンクス研究センター, 所長
WAKAYA Fujio Osaka University, Faculty of Engineering Science, Research Associate, 基礎工学部, 助手 (60240454)
YANAGISAWA Junichi Osaka University, Faculty of Engineering Science, Research Associate, 基礎工学部, 助手 (60239803)
YUBA Yoshihiko Osaka University, Faculty of Engineering Science, Research Associate, 基礎工学部, 助手 (30144447)
AHMED Haroon Univ. of Cambridge, Cavendish Lab., Microelectronics Res. Center
JONES G.A.C. ケンブリッジ大学, キャベンディシュ研究所, 副ディレクター
高原 淳一 大阪大学, 基礎工学部, 特別研究員
|Project Period (FY)
1994 – 1995
Completed (Fiscal Year 1995)
|Budget Amount *help
¥11,700,000 (Direct Cost: ¥11,700,000)
Fiscal Year 1995: ¥5,700,000 (Direct Cost: ¥5,700,000)
Fiscal Year 1994: ¥6,000,000 (Direct Cost: ¥6,000,000)
|Keywords||nanofabrication / electron wave devices / focused ion beam / molecular beam epitaxy / total vacuum process / insitu fabrication process / buried structure / growth interruption / 電子波導波方向性結合器|
The achievements of this year can be divided into the following three subjects.
1. In-situ process
We succeded to form Si island by direct deposition on Au or GaAs substrate using low-energy focused ion beam (FIB). Buried two-demensional electron layrs were fabricated using selective-area doping by low-energy FIB and regrowth by MBE.The carrier profile was measured using C-V method with various anneal conditions. This technique is applicable to fabrication of electron-wave devices.
Growth interruption causes many problems in the total-vacuum processing. Therefore, we investigated the effect growth interruption experimentally and theoretically. It was found that the amount of carrier depletion caused by growth interruption depended on the Si doping concentration. It was concluded by the self-consistent calculation of Schrodinger and Poisson equations that the dependence was due to the shallow interface states. The growth interruption thus causes sever effect in the fabrication process even
in the ultra-high-vacuum chamber. Therefor we investigated the passivation effect using As and found that As passivation is effective to reduce the interface-state density.
2. In-situ processing instrument
In order to reduce the interface-state density caused by the growth interruption, an additional ion pump was added to the chamber for low-energy FIB.We improved the electronic circuit for retarding to achieve fine focus, and it was confirmed that the sub-micron diameter was realized.
3. Electron-wave device
We investigated that the effects of asymmetric bias on the confinement potential in the quantum point contact of metal split gates. We successfully fabricated that an anti-dot superlattice using electron beam lithography (University of Cambridge), Ar ion etching (Osaka University) and reactive ion etching (University of Cambridge), which has the dots of 40-nm diameter and 100-nm pitch.
We developed the selective-area oxidation process using electron beam. We applied the process technique to realize small tunneling barrier of Cr and Cr_2O_3. Less