1998 Fiscal Year Final Research Report Summary
Nano-Scale Structure Control of Organic/Metal Interface and photocurrent Multiplication Device
| Project/Area Number |
09450012
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | Osaka University |
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Principal Investigator |
HIRAMOTO Masahiro Osaka University, Faculty of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (20208854)
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| Co-Investigator(Kenkyū-buntansha) |
YOKOYAMA Masaki Osaka University, Faculty of Engineering, Professor, 大学院・工学研究科, 教授 (90029281)
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| Project Period (FY) |
1997 – 1998
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| Keywords | photocurrent multiplication / organic / metal interface / multiplication-type photosensor / transient response / AFM / tunneling / 原子力間力顕微鏡 / トンネリング |
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| Research Abstract |
We have observed a large photocurrent multiplication reaching 105-fold in various organic films. Aim of research is the clarification of the multiplication mechanism and the application to the multiplication-type photo-sensing device. Following results were obtained.
1. The transient response of the photocurrent multiplication phenomenon was revealed to have two components, which were identified as the primary and the subsequent multiplied photocurrents. This clearly supports the proposed mechanism based on tunneling electron injection from a metal electrode to the organic layer triggered by the photo-accumulated space charges of trapped holes near the organic/metal interface. Based on this result, high speed response of multiplication device was successfully fabricated.
2. Metal film deposited on organic surface was revealed to be a gathering of particles of nanometer scale by atomic force microscopy (AFM), and moreover, the multiplication rate increased with the size of nano-particles. This result confirms that there are the spatially separated parts, I.e., the blind alleys acting as the structural traps at organic/metal interface, which causes the multiplication.
3. By using AEM probe, microscopic observation of surface potential of organic film capturing holes was accomplished. Relation between the structural trap sites and the surface molecular stacking was suggested.
4. Multiplication devices on silicon chip were successfully fabricated. Above results clearly show that the application of multiplication phenomenon to high sensitive photosensor is possible.
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