On the Charge Collection Efficiency of the PERCIVAL Detector

Abstract

the challenges at high brilliance Light Sources such as new-generation Synchrotrons and Free Electron Lasers. Typical requirements for detector systems at these sources are high frame rates, large dynamic range, single-photon counting capability with low probability of false positives, high quantum efficiency, and (multi)-mega-pixel arrangements. PERCIVAL is a monolithic active pixel sensor, based on CMOS technology. It is designed for the soft X-ray regime and, therefore, it is post-processed in order to achieve high quantum efficiency in its primary energy range (250 eV to 1 keV). This work will report on the latest experimental results on charge 1Corresponding author.

Characterization of the Percival detector with soft X-rays

“…The average among ten measurement sets is reported in the graph as a circle, while the error bars represent the standard deviation. As explained by Correa et al (2016), we think the efficiency reduction at 350 eV is due to accidental carbon contamination of the surface (absorption edge 282 eV).…”

“…Characterizations of small-size prototypes of the Percival detector have been presented in the past (Khromova et al, 2016). Similarly, test results were reported on the front-sideilluminated (FSI) version of the full-scale detector (Marras et al, 2019a;Sedgwick et al, 2019a), with visible photons or tender X-rays used to overcome the thick front-oxide of the FSI version.…”

“…We can, however, give a likely estimation of the efficiency, based on CCE measurements that had been done on reduced scale prototypes (Correa et al, 2016) in combination with the information from the Section 3.4. Said prototypes had undergone the same post-processing described in Section 2.2: thus, if there is an inert entrance window preventing some photons to reach the silicon, it should be similar in the prototype as in the P2M detector.…”

“…We can use the CCE values that had been measured on reduced scale prototypes as likely figures of what we can expect of the P2M detector. If we combine the data of Correa et al (2016) with the RCC values measured in Fig. 10(a), we can obtain an estimate of expected QE values for the P2M detector, reported in Fig.…”

P2M: A 2MPixel CMOS Image Sensor for Soft X-Ray Detection

“…This process has already been performed for the test structures previously discussed, and a Charge Collection Efficiency of greater than 80% has been observed down to 400 eV. Even as low as 125 eV, a CCE of 51% has been measured [6].…”