The Research Of Efficient Silicon Single-photon Avalanche Diodes

Information science steps to 21st century after a few decades of rapid improvement following the Moore law and it is facing new challenge because of physical limitations of traditional techniques. In order to break through the bottleneck, quantum information which uses quantum states as information units can push the limits of classical communication systems and lead the information science to a vaster development space.Quantum entanglement is the most important basis of quantum information and entangled eight-photon states have been achieved so far by the means of multi-photon entanglement techniques. However, increasing the photon collection efficiency is a pressing problem in the field of multi-photon entanglement techniques. The photon detection efficiency of single-photon detectors, which are the core components of multi-photon entanglement techniques, plays a decisive part in increasing the photon collection efficiency.Photomultiplier tubes (PMT), superconducting nanowire single-photon detector(SNSPD) based on superconducting materials and single-photon avalanche photodiodes (SPAD) working in Geiger mode are the single-photon detectors most commonly used. The quantum efficiency of PMTs is usually too low to meet the needs of the high detection efficiency. The complicated cooling systems of SNSPDs not only require a high cost but also lack of practicability. SPADs, which are full solid-state, with a simple structure, easily to be integrated and of high quantum efficiency, are almost the only option for practical quantum information systems. Comparing with silicon-based SPADs for detection of visible light and InGaAs/InP-based SPADs for detection of communication wavelength, Si-SPADs are of higher quantum efficiency, but to achieve high detection efficiency all the modules of detection systems have strict specifications. The difficulties of technology application mainly include the sufficiently high excess bias voltage produced by front-end quenching circuits and a strong background noise rejection functioned by back-end avalanche-signal extraction circuits.Therefore, the research of efficient silicon SPAD is of great significance for multi-photon entanglement techniques and even the whole quantum information science.The author's research in the dissertation divides into following several parts:1. Understanding the theory of avalanche photodiodes (APD). APDs are the core of SPADs and understanding the theory of APDs can correlate the external performance of SPADs with the internal physical mechanism to establish the foundation of researching high-performance SPADs.2. Studying the techniques for improving the performance of SPADs and analyzing the difficulties of technology application aimed at the research of efficient Si-SPADs.The key techniques of SPADs contain the semiconductor process technology and electronics technology. Through the studying, it is known that the Si-APDs of the"reach through" technique and gate-mode quenching are appropriate for designing high-efficiency SPADs. However, producing high-voltage gating signal and extracting avalanche signal are the difficulties of applications.3. Designing the efficient Si-SPAD. After designing, more in-depth research of all the function modules in an efficient Si-SPAD detection system and the effective methods for improving the performance has been done. After breaking through the difficulties, it is more deeply understanding how to design a Si-SPAD of good performance.4. Setting up the test bench, testing the performance of the Si-SPAD designed by the author and comparing the results with the performance of other Si-SPADs. From the test results, it shows the corresponding relationship between the performance of the detector and the specifications of each module in the detector. By the comparison, it is proven that the research methods and research routes are correct.In the research, the author has made the following innovative work:1. Improving the detection efficiency of SPADs and developing an efficient silicon SPAD with 74.5 % of detection efficiency, which is 6 % higher than SPADs with the same avalanche photodiodes of commercial version. For ten-photon entanglement experiments, it will increase about 79 % of the collection efficiency.2. Adopting RF amplifying techniques to design a RF power amplifier with high linearity, which amplifies the original signal by 36 dB and outputs signals of 38 dBm.The amplifier produces high-voltage gating signals which improves detection efficiency of Si-SPADs.3. Applying sinusoid filtering to design efficient Si-SPADs and rejecting the background noise by 55 dB to successfully extract the weak avalanche signals.