Improved Noise Performance of CMOS Poly Gate Single-Photon Avalanche Diodes
The noise performance of three types of n<sup>+</sup>/p-well single-photon avalanche diodes (SPADs) fabricated in a standard 180 nm CMOS technology is studied. The SPADs had different poly gate configurations: no poly gate (SPAD_NG), a dummy floating poly gate (SPAD...
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| Main Authors: | , , |
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| Format: | article |
| Language: | EN |
| Published: |
IEEE
2022
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| Subjects: | |
| Online Access: | https://doaj.org/article/c3c0fd1ae8f040ab869719ea2b111f1c |
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| Summary: | The noise performance of three types of n<sup>+</sup>/p-well single-photon avalanche diodes (SPADs) fabricated in a standard 180 nm CMOS technology is studied. The SPADs had different poly gate configurations: no poly gate (SPAD_NG), a dummy floating poly gate (SPAD_DG), and a field poly gate connected to the n<sup>+</sup> cathode (SPAD_FG). The measurement results of dark count rate and afterpulsing showed that the SPAD_DG had better noise performance compared to the SPAD_NG. This is because the dummy poly gate pushed the shallow trench isolation away from the active region of the SPAD, thus reducing the dark noise generated from the Si-SiO<sub>2</sub> interface. The measurement results also revealed that the noise performance can be further improved by connecting the poly gate to the n<sup>+</sup> cathode. The voltage on the poly gate in SPAD_FG reduced the electric field in the n-well guard ring (GR) region, thus reducing the carriers from the GR region that can enter the active region of SPADs and initiate dark counts. |
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