FAST, HIGH-DENSITY AVALANCHE PHOTODIODE-ARRAY

Using bevelled edge avalanche photodiode technology, we have built a h igh density 64-element array, with center-to-center spacing of 450 mum . The array was built by etching grooves in the back side of a large a rea avalanche photodiode. The pattern for etching and metalization of the pixels on the back side was done with photolithography. This techn ique allows for good control of the groove depth. The cross talk betwe en pixels is related to the resistance between them and is dependent o n the bias applied to the detector. Because of the small pixel size, t he rise time with an impulse excitation approaches approximately 0.9 n s. These arrays have very good potential for light or low energy x-ray imaging systems and optical fiber readout in detectors for high energ y physics detectors.