Via-in-pixel design of truly 2D extendable photodiode detector for medical CT imaging

Fan Ji (Corresponding Author), Juha Kalliopuska, Simo Eränen, Mikko Juntunen, Iiro Hietanen, Seppo Leppävuori

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)


This paper presents a new design of the silicon-based photodiode detector for medical imaging, especially for the X-ray computed tomography applications. The new structure of the photodiode includes a conventional front-illuminated photodiode and a through wafer interconnection. Moreover, the through wafer interconnection is integrated into the photodiode by being placed inside the active area of the photodiode. This new structure is called via-in-pixel design. Truly 2D photodiode detector can be designed with maximum free space or minimum gap between each two photodiode elements by using the via-in-pixel design. In addition, 2D photodiode detector arrays can be constructed by tiling more edgeless detectors. In the paper, the via-in-pixel photodiodes were demonstrated and the performances were measured. Together with the measurement data, a quasi-3D device simulation was performed to disclose the electrical characteristics of the via-in-pixel photodiode by using Synopsis Advanced TCAD software. The results show that the via-in-pixel design of the photodiode detector can either meet or exceed the medical imaging requirements.
Original languageEnglish
Pages (from-to)59-65
JournalSensors and Actuators A: Physical
Publication statusPublished - 2008
MoE publication typeA1 Journal article-refereed


  • Via-in-pixel design
  • Computed tomography
  • Photodiode detector
  • Through wafer interconnection


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