Large-area APDs and monolithic APD arrays

In this paper, development of large-area planar avalanche photodiodes (APDs) and monolithic APD arrays for X-ray and scintillation detection is discussed. Single APDs with areas as large as 10 cm/sup 2/ have been fabricated and tested with a CsI(Tl) scintillator (3.8 cm diameter, 2.5 cm height). The resolution of the 662 keV photopeak has been measured to be 9% (FWHM). The X-ray detection performance, gain, and noise of these large APDs have been characterized. Multielement APD arrays have also been fabricated in various formats, such as 4/spl times/4 to 14/spl times/14 elements (2 mm pixels), and the uniformity of gain, noise, and sensitivity has been evaluated for 4/spl times/4 arrays using an /sup 55/Fe source. Timing properties have been measured. Packaging issues related to the APD arrays are discussed.