APD photodetectors in the Geiger photon counter mode

Geiger APD technology, which has been used for a few years now [R.H. Haitz, J. Appl. Phys. 35 (5) (1964) 1370], is evolving towards better performances, including integration in multifunctional microsystems; one such achievement today is the so-called SiPM [P. Buzhan, et al., Nucl. Instr. and Meth. A 567 (2006) 78]. The present work has been conducted by a consortium of researchers from CESR and LAAS/CNRS and the manufacturing of components was achieved in the clean room of LAAS/CNRS. We present here an original N/P technology of photodiode, designed so as to offer a very good homogeneity in the electrical operating characteristics. For this, we have chosen a design and technological process that defines the breakdown voltage from the substrate doping. We present the technological process we developed, in which we took special care to maintain, by low transit temperature processes, at the highest quality level the initial characteristics of the materials. We will also present the performances of the diodes produced, with sizes ranging from 10 to 100 μm, as a function of many parameters (gain, dark current, etc). We also produced SiPM, and also 8x8 arrays of SiPM. Typical characteristics for a single diode are a Vbr between 43 and 44 V, and a dark current below 1 pA at ambient temperature. But the most important feature seems to be the high homogeneity of these performances all over the wafer surface. This gives us great confidence in the next step of our work, which is the manufacturing of very high-sensitivity imaging devices.