Development of layered type CVD single aystal diamond radiation detectors

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In this fiscal year, improvement on fabrication of layred type CVD diamond radiation detectors. In the previous year, we tried to fabricate the layred type CVD single diamond radiation detector by using a high-quality boron doped diamond layer that was flat in atom scale. However, this trial was failed because abnormal growth on the boron doped layer. Thus, we applied previously used process for fabrication of boron-doped layer. In this process, we found out that grown diamond layer obtained large influence from surface morphology of a type Ib single diamond substrate. Then, we evaluate a relation between mechanical polishing process and grown diamond layer. In previously used process, type Ib diamond substrate mechanically polished for one direction was used. Recently a diamond substrate supplier changed their way to polish a diamond substrate. The supplier polished a diamond substrate from random directions in order to obtained better optical flatness. However, this process destroyed surface crystal structure, and it resulted in bad quality in grown diamond layer. Then we asked to change the substrate supplier for their polishing process for suitable way to diamond growth, and it resulted in better growth of diamond layer. In addition, we tried to fabricate a layered type CVD diamond radiation detector by using high-quality single diamond substrate. This substrate include only 0.1 to 0.3 ppm of boron impurities and it was semiconductor. Moreover, charge carriers' transport phenomenon measurement system 213 nm UV pulse laser system was developed. Charge carriers' transport phenomenon in the layered type diamond radiation detectors, single and polycrystalline diamond were evaluated by using this system. 14 MeV neutron response function measurements using the layered type CVD single diamond radiation detector was carried out.