Novel single photon sensors for highly sensitive fluorescence detection systems

This dissertation is focused on studies of two types of low cost solid-state photodiodes working as single photon detectors and their applications for highly sensitive fluorescence detection systems.;An operation of the commercial linear avalanche photodiode (Hamamatsu Si APD S9073) has been studied in conjunction with a novel, unique quenching circuit. The operation of the diode in Geiger-mode has been experimentally demonstrated with dead time of ∼50ns. Studies of the dark count of the un-cooled diode showed a very significant enhancement of the dark count with increase of the over-voltage. It has been found that at the over-voltages needed for sensitive photon detection, the dark count reaches 107/sec that puts the diode in the saturation region due to a relatively long quenching delay. The conclusion has been made that for an efficient single photon counting, one needs to cool the diode and to decrease the quenching delay. The schematic of quenching circuit that makes the dead time smaller and less area consuming has been designed in standard 0.6um CMOS technology and simulated using Cadence tools.;A novel type of single photon diode, Silicon Photomultiplier (SiPM), has been studied in single photon counting mode. For the first time, the application of SiPM with external amplifiers for single photon detection to DNA sequencing has been demonstrated. A novel SiPM design, which requires neither external quenching nor amplification for photon counting has been proposed utilizing the unique performance of SiPM, optical cross-talk. A simulator has been developed based on the model of SiPM in Python. The output pulse distribution with different cross-talk probabilities and afterpulsing probabilities has been simulated. Experiments on SiPMs from two manufactures have been done and presented in the dissertation.