Planar APD arrays for high-resolution PET

In this paper, characterization of new, planar silicon avalanche photodiode arrays for high-resolution PET applications is discussed. High gain, monolithic 4 X 4 element APD arrays (2 mm pixels) have been fabricated using planar processes. These devices were characterized by measuring their gain (> 103), quantum efficiency (60% at LSO emission) and noise (200 eV FWHM). Energy and timing resolution of these APDs were also measured by coupling them to LSO scintillators (2 X 2 X 10 mm) and were found to be 12% and 4 ns, respectively. An APD array was also coupled to a matching LSO array and successful experiments were conducted to identify the crystal which scintillated. Finally, initial experiments to measure depth of interaction have also been performed.