Research

Recent Themes

We introduce main research themes of this laboratory.

1.The development of microwave atomic force microscopy (M-AFM)

With the development of nanotechnology, the method for observing and evaluating materials at atomic scale is necessary. Various measurement methods are being developed for application. However, although the quantitative evaluation of electrical properties such as conductivity and their distribution is expected in the development of new generation devices or in the analysis of biological tissues, it has not been realized yet. In order to resolve this issue, the probe of atomic force microscopy (AFM) was fabricated by GaAs, which has several advantages over Si. With this technology, the quantitative evaluation of electrical properties at nanoscale can be expected in the future.

AFMの原理表面形状像電的気特性像
Topological image and electrical property image of M-AFM.
GaAsカンチレバーのSEM写真
The SEM image of GaAs cantilever.

2.A Study on Creation and Evaluation of Functional Nanowire Surface Fastener

Metallic nanowires have some remarkable characteristics such as mechanical, electrical and bonding properties. We propose metallic nanowire surface fastener (NSF) for a new surface mount technology which can connect at room temperature. Metallic NSF can be connected at room temperature by utilizing van der Waals force for the connection of electrical components. Furthermore, it has a good heat resistance because the metallic nanowire has a high melting point. We try to fabricate metallic NSF which has high density and ordered nanowires and establish an evaluation method for its properties.

ポーラスアルミナテンプレート観察写真
Porous alumina template
高密度金属ナノワイヤの観察写真
High density metal nanowires

3.Creation and Evaluation of Semiconductor Nanostructures by Stress Migration

Semiconductor nanowires are expected to be applied as next-generation solar cells and nano-device integrated circuits. Bottom-up technology combining elements at the atomic and molecular level has attracted attention as a method of forming nano-scale microstructures. In this research, semiconductor nanowires are fabricated by wire rearrangement of atoms diffused by the thermal stress gradient as a driving force. Furthermore, we aim to evaluate the mechanical and electrical properties of fabricated semiconductor nanowires and create new utility value.

高密度ナノワイヤ
High density nanowires
ヒロック上の長ナノワイヤ
Long nanowire over hillock

4.A Study on Restoration of Fatigue Crack on Metal Surface

Approximately 80% of all failure accidents in metal materials are due to metal fatigue. A lot of studies have used the methods such as carburizing and nitriding, high-frequency quenching, shot-peening to improve the fatigue strength; however, there is no established technique of restoring the metal material’s fatigue crack and delaying the progress of fatigue failure.
In this study, we use the closing electric terminal at the metal material’s fatigue crack, make electric current concentrate around the fatigue crack tip, and utilize the effect of electronic energy by controlling the high density pulsed current to restore the fatigue crack and delay the progress of that. We also aim to clarify the mechanism.
By realizing of this technique, it is possible to improve the long-term reliability of the structure markedly and also has an effect to decrease the maintenance cost and the environmental loading.

ステンレス鋼の疲労き裂修過程
The process of restoring the fatigue crack of stainless steel
機械構造物の破壊事例の原因別分類
Causes of failure accident in metal materials