Greiffenberg, Dominic, Marie Andrä, Rebecca Barten, Anna Bergamaschi, Martin Brückner, Paolo Busca, Sabina Chiriotti, Ivan Chsherbakov, Roberto Dinapoli, Pablo Fajardo, Erik Fröjdh, Shqipe Hasanaj, Pawel Kozlowski, Carlos Lopez Cuenca, Anastassiya Lozinskaya, Markus Meyer, Davide Mezza, Aldo Mozzanica, Sophie Redford, Marie Ruat, Christian Ruder, Bernd Schmitt, Dhanya Thattil, Gemma Tinti, Oleg Tolbanov, Anton Tyazhev, Seraphin Vetter, Andrei Zarubin, and Jiaguo Zhang. Characterization of Chromium Compensated GaAs Sensors with the Charge-Integrating JUNGFRAU Readout Chip by Means of a Highly Collimated Pencil Beam. Greiffenberg D, Andrä M, Barten R, Bergamaschi A, Brückner M, Busca P, Chiriotti S, Chsherbakov I, Dinapoli R, Fajardo P, Fröjdh E, Hasanaj S, Kozlowski P, Lopez Cuenca C, Lozinskaya A, Meyer M, Mezza D, Mozzanica A, Redford S, Ruat M, Ruder C, Schmitt B, Thattil D, Tinti G, Tolbanov O, Tyazhev A, Vetter S, Zarubin A, Zhang J. A focused photon beam was used to illuminate well defined positions along the pixels in order to corroborate the findings from the previous work and to further characterize the consequences of the “crater effect” on the detector operation. The hole lifetime of these sensors was 2.5 ns. In this publication, the “crater effect” is further elaborated by measuring GaAs:Cr sensors using the sensors from 2017. In a previous work, a hole lifetime of 1.4 ns for GaAs:Cr sensors was determined for the sensors of the 2016 sensor batch, explaining the so-called “crater effect” which describes the occurrence of negative signals in the pixels around a pixel with a photon hit due to the missing hole contribution to the overall signal causing an incomplete signal induction. Likely, this is due to improvements in charge collection, lower noise, and more homogeneous effective pixel size. Moreover, its noise performance is 14% lower with a value of (101.65 ± 0.04) e − ENC and the resolution of a monochromatic 60 keV photo peak is significantly improved by 38% to a FWHM of 4.3%. The properties of the sample from the later batch of sensors from 2017 show a resistivity of 1.69 × 10 9 Ω/cm, which is 47% higher compared to the previous batch from 2016. Sensor properties such as dark current, resistivity, noise performance, spectral resolution capability and charge transport properties were measured and compared with results from a previous batch of GaAs:Cr sensors which were produced from wafers obtained from a different supplier. Chromium compensated GaAs or GaAs:Cr sensors provided by the Tomsk State University (Russia) were characterized using the low noise, charge integrating readout chip JUNGFRAU with a pixel pitch of 75 × 75 µm 2 regarding its application as an X-ray detector at synchrotrons sources or FELs.
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