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Irradiation of Si-Structures

#0775


Mesoscopic Phenomenon in Disordered Si-based Structures at Neutrons and Gamma-rays Irradiation

Tech Area / Field

  • PHY-SSP/Solid State Physics/Physics

Status
3 Approved without Funding

Registration date
27.10.1996

Leading Institute
Siberian Branch of RAS / Institute of Semiconductor Physics, Russia, Novosibirsk reg., Novosibirsk

Supporting institutes

  • VNIITF, Russia, Chelyabinsk reg., Snezhinsk

Collaborators

  • Technische Universität Berlin / Institute für Optik und Atomare Physik, Germany, Berlin\nForschungszentrum Rossendorf / Institut für Ionenstrahlphysik und Materialforschung, Germany, Dresden\nUniversity of Cambridge, UK, Cambridge

Project summary

The reduction of system dimension leads to the changing of its properties as compared with macroscopic systems. The reason is that macroscopic system allows averaging the characteristics over large ways of realization. The effect of absence self-averaging in microstructures is often defined as mesoscopic phenomena. High sensitivity of mesoscopic structures on external action is very attractive for sensor application. But serious limitation to make the idea of mesoscopic devices reality was the low temperature of operation (~ 4 K). Recently scientists of Institute of Semiconductor Physics discovered mesoscopic phenomena at room temperature. One of phenomenon is two-level switching of hopping current in silicon structures with thin layers of amorphous silicon (a-Si) and small area of current contacts. The project's authors have found the phenomenon of conduction switching induced by ultra-violet illuminations. This is physical background for the proposed Project.

The aim of the present Project is to study mesoscopic phenomena induced by gamma-ray and neutron particle irradiation of amorphous Si based nanostructures. The operation range and physical limitations of mesoscopic structures as radiation detectors will be revealed in the proposed project.

The experimental studies and modeling of conduction switching in mesoscopic structures at gamma-ray, fusion- and fission neutron irradiation will be made. The parameters of mesoscopic detectors and the nature of conduction switching induced by irradiation are planned to be determined. As a technical approach the technology of mesocsopic structure fabrication, Co-60 gamma-ray source, neutron (fusion) generator and pulsed fission-neutron reactor will be used.

The ideal source for induced conductivity switching studies in mesoscopic structures is equipment allowing generating monochromatic flux of gamma-rays and neutron particles. In this case one may easily estimate contribution of displacement atoms and ionization losses to understand more complicate experiments with irradiation from nuclear reactor.

Anticipated results:


- The technology of mesoscopic structure preparation will be developed to reveal mesoscopic phenomena in disordered-Si based structure with gamma-ray, fast-neutron and fission-neutron irradiation. The optimal parameters of mesoscopic devices will be determined.
- The mechanism of induced conduction switching at the gamma-ray and neutron irradiation of mesoscopic structure will be studied.
- The operation range and physical limitations of the radiation detectors based on mesoscopic phenomena will be determined in structures with amorphous Si and porous a-Si layers.
- The experimental radiation detectors will be fabricated and its performances will be tested.

The mesoscopic structures based on disordered Si are expected to be used for large-area images. Use of amorphous Si layers in flat-panel displays has paved the way for new generation of electronic X-ray, gamma-ray and neutron-particle imaging devices. Diagnostic medicine is just one of a multitude of applications for large-area array a-Si detectors. Other examples include noncontact inspection of pipelines - looking for cracks and voids - inspection of foods for the presence of foreign materials, monitoring of nuclear reactor irradiation.

The potential role of foreign collaborators is the fundamental studies of mesoscopic structures (fabrication, measurements and research) in the frame of co-operation of Institute Semiconductor Physics scientists with colleagues from Germany, England, and France.


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