Presentation Transient Current Induced in Thin Film Diamonds by Swift Heavy Ions

佐藤, 真一郎

Introduction: High energy ion microbeam outside a vacuum system is a valuable tool for investigation of localized radiation effects in samples that are unsuitable for mounting inside the vacuum chamber (e.g. biological samples and medical use). In order to obtain in-situ monitoring of microbeam outside vacuum, thin film diamonds are considered to be utilized for both single-hit particle detector and vacuum window. The purpose of this study is to clarify fundamental characteristics of thin film diamond devices as particle detectors. Methods: Sample were single-crystalline diamonds with the thickness of 50 and 6 microns. Aluminium electrodes were formed on both sides of the samples to collect generated charges by incident ions (26 MeV O5+ and 45 MeV Si7+). Transient currents generated when single ions hit the sample and their positional information were measured, and the 2D mapping of the transient currents was recorded. A bias voltage from -50 V to +50 V was applied to the samples and the variation of transient currents due to applied bias voltages was investigated.Results and discussion: In the case of 50 micron thick sample, lower signals appeared for a while after a larger signal appeared and this phenomenon repeated throughout measurements. This is thought to be due to polarization effect of the sample. In the case of 6 micron thick sample, inhomogeneous 2D mappings of the transient currents were obtained. It is likely that areas where lower signals appeared have poorer crystal quality and the charge collection efficiency is lower than the other areas, or the inhomogeneous 2D mapping reflects non-uniformity of the thickness.Conclusions: The crystal quality of thin film diamonds, their uniformity of thickness, and the polarization effect were characterized by analysing the collection process of ion-induced charges and its 2D images.
The 27th International Conference on Diamond and Carbon Materialsに参加し、研究成果発表を行うため。

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