Development of layered type CVD single aystal diamond radiation detectors

在本财政年度，对层叠式CVD金刚石辐射探测器的制造进行了改进。在过去的一年里，我们尝试用原子尺度平坦的高质量的掺硼金刚石层来制作层叠式CVD单金刚石辐射探测器。然而，由于掺硼层上的异常生长，这次试验失败了。因此，我们采用了以前使用的工艺来制备掺硼层。在此过程中，我们发现生长出的金刚石层受Ib型单晶金刚石衬底表面形貌的影响很大。然后，我们评估了机械抛光工艺与生长的金刚石层之间的关系。在以前使用的工艺中，使用了单向机械抛光的Ib型金刚石基板。最近，一家钻石基板供应商改变了抛光钻石基板的方式。供应商从任意方向抛光金刚石衬底，以获得更好的光学平坦度。但这一过程破坏了金刚石表面的晶体结构，导致生长出的金刚石层质量较差。然后我们要求改变他们的抛光工艺的衬底供应商，以适合金刚石的生长方式，这导致了更好的金刚石层生长。此外，我们还尝试用高质量的单金刚石衬底来制作层状CVD金刚石辐射探测器。这种衬底只包含0.1到0.3ppm的硼杂质，而且它是半导体的。此外，还研制了载流子输运现象测量系统和213 nm紫外光脉冲激光系统。利用该系统对层状金刚石辐射探测器、单晶和多晶金刚石中的载流子输运现象进行了研究。用层状CVD单金刚石辐射探测器测量了14 MeV的中子响应函数。

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.