Abstract: A wafer of neutron transmutation doped silicon having a p-n junction between extended opposite surfaces is formed with bevelled edges. A single or plurality of reverse biased signal contacts is disposed on one surface to provide a single or integrated array of avalanche photodiodes. In addition, an avalanche photodetector (APD) capable of detecting a single photoelectron or imaging multiple photoelectrons comprises a light sensitive photocathode, similar to that in a photomultiplier tube, acting as a converter to produce photoelectrons, which are then accelerated to an anode. The anode comprises a single avalanche photodiode (AP) for detecting or an array (APA) for imaging photoelectrons. The energetic photoelectrons striking the AP or the APA serve as the AP or APA's input signal, respectively.

Abstract: Large area semiconductor photodiodes are made free of microcracks by forming on the incident light surface of the device a ring-shaped electrode structure. The electrode structure adds rigidity to the device when the edge surface of the device is later bevelled, a process which creates microcracks normally.

Abstract: A wafer of neutron transmutation doped silicon having a pn junction between extended opposite surfaces is formed with bevelled edges. A plurality of reverse biased signal contacts is disposed on one surface to provide an integrated array of avalanche photodiodes.