Development and fabrication of microdosimeter arrays based on single-crystal diamond Schottky diodes

The interest in microdosimetry is growing thanks to the advancement in microdosimetric technologies, improving detector performance and reliability. Herein, the fabrication and characterization of a novel diamond-based microdosimeter are proposed. The microdosimeter consists of an array of single-crystal diamond Schottky diodes about 1.5 mu m thick connected in parallel. The detector prototypes are characterized using the ion beam-induced charge technique, employing a 6 MeV carbon ions microbeam. Despite a good overall response, the first prototypes are affected by the "bridge effect": a charge collection beneath the metallic bridges connecting the sensitive volumes (SVs), which alters the energy deposition spectrum. To mitigate the bridge effect, different technological solutions are explored: the selective growth of intrinsic diamond layers and the use of an insulating material such as photoresist. These second prototypes reveal a good SV spatial definition without any charge collection from the bridges and a good response homogeneity within the SVs ranging between 3% and 5% full-width-half-maximum among the different prototypes. While the cell-like thickness and lateral dimensions of SVs make the diamond microdosimeter array ideal for radiobiological applications, its array configuration can make it highly versatile to perform under different fluence rate conditions in particle therapy.Herein, a novel diamond array detector is reported for high spatial resolution microdosimetry. The novel technology succeeds in performing without any undesired charge collection from the metallic bridges connecting the sensitive volumes. To the authors' knowledge, this is the first time a diamond array detector achieves this result proving such sensitive volume definition.