A novel photodiode array structure for gamma camera applications

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Vol. 504; no. 1-3; pp. 188 - 195
• Main Authors: Evrard, O., Keters, M., Van Buul, L., Burger, P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 21.05.2003
• Subjects: Anti-reflective coating; Photodiode; Pixel detector; Quantum efficiency; Pixel detector; Anti-reflective coating; Quantum efficiency; Photodiode
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/S0168-9002(03)00789-7

Photodiodes coupled to scintillators are more and more used for gamma camera applications in order to improve the efficiency at higher energies. However the coupling of photodiode arrays become difficult when the pixel number is large because of the complicated front and backside connections with read-out electronics. Canberra has developed a photodiode array structure that allows all electrical connections to be taken on one side, while the light entrance side can be directly glued on the scintillator. Using such a photodiode array, the dimensions of the scintillator can be the same as the silicon chip and near 100% of the area will detect light. Furthermore, an array of photodiodes coupled to scintillators can be built without any dead gap in between. To improve the quantum efficiency of the photodiodes, we had to develop a thin ohmic entrance window covered by an anti-reflective coating. A quantum efficiency of more than 80% at 565nm was achieved.