| Single photon detectors are increasingly needed in the emerging fields of quantum computation and quantum cryptography as well as in some more traditional fields that requiring single photon sensitivity. As in the telecom wavelengths of 1310 and 1550nm, a separate absorption, grading, charge and multiplication (SAGCM) In0.53Ga0.47As/InP avalanche photodiode (APD) that reverse biased beyond breakdown voltage (VB) and operated in so-called Geiger mode is regarded as one of the most practical single photon detectors. These APDs are also known as Geiger mode avalanche photodiodes or single photon avalanche diodes (SPADs).In this thesis, characteristics of the avalanche breakdown in SAGCM In0.53Ga0.47As/InP SPADs are analyzed numerically and experimentally. In the experiment, saturation of the relative current gain is observed and interpreted. According to this, the punch-through voltage and breakdown voltage of single photon avalanche diodes can be measured in a simple and accurate way. The analysis method is temperature independent and more practical.The structure and operation dependence of breakdown voltage is also calculated. The results indicate that the breakdown voltage increases with the temperature and charge density in the charge layer. And there is a critical value of the multiplication layer width Wm0. When the multiplicition layer width (Wm) is smaller than Wm0, VB decreases with Wm. While VB increases slowly with when Wm is above Wm0. An improved structure of In0.53Ga0.47As/InP SPAD is proposed in which the width and doping concentration of the multiplication, absorption and charge layer is carefully designed specially for single photon detection.In order to optimize the structure design and operation of SPADs, it is necessary to clarify the mechanisms that give rise to dark counts, as well as the dependence of SPQE and Pd on the structure, voltage and temperature. In the thesis, a more rigorous model is developed to determine the SPQE and Pb, in which impact ionization in charge and absorption layers have been taken into account to have contribution to the avalanche breakdown which can take place only in the multiplication region. In the temperature range of 200-300K, dark count rate of SPADs with 0.2-3μm multiplication layer was calculated. Results show that, ignoring the impact ionization of charge and absorption layer will cause an underestimate of dark counts. The ratio of underestimate increases with temperature. The results also show that the primary mechanism of dark counts depends on both device structure and operating conditions. The thickness of charge layer greatly affects the dark counts and peak SPQE. The peak SPQE rises with the increase of multiplication layer width. But when Wm > 1μm, the peak SPQE increases slowly and it finally saturates at the quantum efficiency of the SPAD. The primary origin of dark counts depends on both device structure and operating conditions. For SPADs with thinner multiplication layer, band to band tunneling in multiplication layer is the dominative mechanism of dark counts, while for thicker SPADs, generation-recombination in the absorber dominates the dark counts. Dark counts from generation-recombination increase importance with temperature. As for a SPAD with multiplication layer arround 1μm, there is a critical temperature, when the operating temperature below the critical temperature, tunneling is the primary origin of dark counts, while when the operating temperature exceed the critical temperature, generation-recombination in the absorption layer begins to dominate.An integral gated mode single photon detector is demonstrated at telecom wavelengths. The charge number of an avalanche pulse rather than the peak current is monitored for single photon detection. The transient spikes in conventional gate mode operation are cancelled completely by integrating, which effectively improves the performance of the single photon detector. This method may achieve a detection efficiency of 29.9% at the dark count probability per gate equals to 5.57×10-6/gate (1.11×10-7/ns) at 1550nm.
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