Evaluation of X-ray astronomical SOI CMOS pixel sensor aimed at - PowerPoint PPT Presentation

Evaluation of X-ray astronomical SOI CMOS pixel sensor aimed at improvement charge-collection efficiency Masataka Yukumoto (University of Miyazaki) yukumoto@astro.miyazaki-u.ac.jp T. Hida, K. Mori, Y. Nishioka, A. Takeda, K. Fukuda, K. Taniguchi, A. Danno (University of Miyazaki), T. G. Tsuru, T. Tanaka, S. Harada, K. Kayama (Kyoto University) , H. Matsumura (Kavli IPMU), Y. Arai, Ikuo. Kurachi (KEK), T. Kohmura, K. Hagino, K. Negishi, K. Oono, K. Yarita (Tokyo University of Science)

2 Contents ・ Introduction ・ Spectrum measurement by using XRPIX6H ・ Subpixel response experiment ・ Summary PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

3 SOI pixel sensor for X-ray astronomical use Cross section of our device “XRPIX” ・ XRPIX is a monolithic active pixel sensor with Silicon-On-Insulator (SOI) CMOS Technology. ・ Two substrate are formed monolithically and have a different resistivity. Ideal for X-ray ・ The thick depletion layer and advanced signal processing are compatible. astronomical use PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

4 History of XRPIX Series 2011 2013 2010 2012 2014 Previous First Model research Trigger Output Previous Charge Sensitive Amplifier (Event-driven readout) research Middle Size Buttable 2014 2015 2016 This experiment µ Pixel Structure New Readout Circuit Large Size

5 Charge sharing One pixel X-ray X-ray Single Triple Double or Quadruple Cross section of imaging area Top view of left figure ・ Depending on the intra-pixel position where X-ray is photo-absorbed , electric charges generated are collected by a single pixel or shared by multiple pixels PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

6 The effects of in-pixel circuitry on the sensor layer Matsumura et al. (2015) Single pixel event Double Tail pixel event Peak shift + + + + + + Cross section of one pixel Spectrum of Am X-ray obtained with XRPIX1b ・ The BPW formed at pixel center fixes potential to suppress the back-gate effect. ・ The in-pixel circuitry placed outside the BPW distorts the electric field of the sensor layer. ・ The circuitry causes charge loss at the pixel boundary and peak shift in the spectra of multi pixel event. PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

7 Rearranging the placement of in-pixel circuitry Matsumura et al. (2015) In-pixel circuitry placement of XRPIX1b In-pixel circuitry placement of XRPIX2b ・ There is the circuitry at the pixel boundary in XRPIX1b. ・ In XRPIX2b, the placement of the circuitry is re-arranged near the BPW ・ The aim is improving the Charge-Collection Efficiency (CCE) at the pixel boundary. PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

8 Partial improvement of the CCE Matsumura et al. (2015) Matsumura et al. (2015) Single pixel event Double Tail Tail pixel event Peak shift Spectrum of Am X-ray obtained with XRPIX2b Spectrum of Am X-ray obtained with XRPIX1b ・ Peak shift disappeared however Tail had been appearing in spectrum of XRPIX2b. ・ Require further improvement Development of XRPIX6H PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

9 Contents ・ Introduction ・ Spectrum measurement by using XRPIX6H ・ Subpixel response experiment ・ Summary PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

10 The difference between XRPIX2b and XRPIX6H In-pixel circuitry placement of XRPIX2b In-pixel circuitry placement of XRPIX6H ・ There is the circuitry outside the BPW in XRPIX2b. ・ Rearrange the placement of the circuitry inside the BPW in XRPIX6H. ・ Aiming the further improvement the CCE at the pixel boundary. PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

11 Improvement of spectral shape Single 241 Am 241 Am pixel event Double pixel event Tail Spectrum of 241 Am X-ray obtained with XRPIX2b Spectrum of 241 Am X-ray obtained with XRPIX6H ・ Tail disappear in spectrum of Double pixel event. ・ It is suggested that the CCE at pixel the boundary was improved in XRPIX6H PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

12 Contents ・ Introduction ・ Spectrum measurement by using XRPIX6H ・ Subpixel response experiment ・ Summary PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

13 Subpixel response experiment ・ Irradiate the small part of one pixel with collimated X-ray beam. ・ Move the device by positioning automatic stage. ・ This experiment enables us to decide relative incident position in one pixel. PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

14 Experimental setup The device and the board The automatic positioning stage The collimator Inside the vacuum chamber Experimental setup PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

15 Spectra in each position Mo 36 μm Near the pixel boundary - Mo Kα is not observed. Mo - Spectral shape is bad. 36 μm Mo Kα Near the pixel center - Mo Kα is observed. ・ Spectral shape is different and rate of single pixel event change in each position. ・ The position-dependence of the spectrum is seen in one pixel. PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

16 Countmap in each position Mo Kα Count map of single pixel event Count map of all pixel event ・ The fraction of single pixel event is the highest at the pixel center and decreases toward the pixel boundary. ・ Although the ratio between the single and multi pixel events changes, total number of events does not change PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

17 Contents ・ Introduction ・ Spectrum measurement by using XRPIX6H ・ Subpixel response experiment ・ Summary PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto

18 Summary ・ We have been developing the active pixel sensor with SOI CMOS technology for X-ray astronomical use. ・ We developed the XRPIX6H in which the in-pixel circuitry is spatially arranged inside the BPW ・ XRPIX6H shows little difference between single and double pixel event spectra ・ Sub-pixel response experiment confirms that the fraction of single pixel event is the highest at the pixel center and decreases toward the pixel boundary. • These results show the CCE at the pixel boundary is improved PIXEL2018@Taipei, Taiwan Dec10-14 M.Yukumoto