Technology and Performance Study of a Two-Line Monolithic X- and \gamma-Ray Detection Chip Based on Semi-Insulating GaAs

• Published in: IEEE transactions on nuclear science 2011-12, Vol.58 (6), p.3354-3358
• Main Authors: Bohacek, P., Dubecky, F., Zat'ko, B., Sekacova, M., Huran, J., Necas, V., Mudron, J.
• Format: Article
• Language: English
• Subjects: Bias; Chips; Current density; Electric potential; Gallium arsenide; Gallium arsenides; Metallization; Pixel radiation detector; Pixels; Radiation detectors; semi-insulating GaAs; Voltage; X-ray and gamma -ray detection; X-ray detection; X-ray imaging
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/TNS.2011.2170706

Technology, electrical characteristics and detection performance of a novel recently developed and fabricated 64-pixel two-line array chip for detection of X- and γ -rays based on semi-insulating GaAs from three different producers are reported and compared. The chip has dimensions of cca (16 × 4 × 0.25) mm 3 . A single pixel has an active area of (300 × 190) μm 2 with a pitch of 250 μm. The distance between two lines is 360 μm. The reverse current density (at 295 K) of a single pixel at a bias voltage of 200 V ranges from 90 to 140 nA/mm 2 . The breakdown voltage ranges between 250 and 500 V. Pulse-height spectra of radionuclide 241 Am in the top irradiation mode are demonstrated. The best spectrometric performance is achieved with the Freiberger material. The charge collection efficiency of about 85% and energy resolution in the full width at half maximum better than 8.6 keV for the 59.5 keV photopeak was reached at 295 K and bias of 300 V.