University of Cambridge
Single-photon avalanche photodiodes for quantum communication applications in the near-infrared
Abstract
dc:description.abstractThis thesis describes the experimental research undertaken on InGaAs-InP single-photon avalanche photodiodes (SPADs) intended for use in near-infrared (NIR) applications, such as light detection and ranging (LIDAR) and quantum key distribution (QKD) systems. Within the work, the effect of the lateral dimensions of the detector’s anode on the experimental characteristics that are used to quantify performance of the SPAD in the gated operating mode, namely the dark count rate (DCR) of the detector, is defined for the first time. It is shown that while the measured dark current increases with the width of the attached guard ring (AGR), the DCR decreases with increasing AGR width, indicating that anode geometry is a more appropriate indicator of DCR performance than dark current. For optimum geometries, DCRs of ∼1×10<sup>-6</sup> ns<sup>-1</sup> are observed for SPADs cooled to a TEC-accessible temperature of 243 K. The work then concentrates on a SPAD’s location on both a wafer-scale and cell-scale on MOVPE-grown wafers of SPADs, and the impact on the experimental characteristics that are used to quantify performance, primarily the DC characteristics breakdown voltage and dark current. Two wafers were measured, with both resulting in higher dark currents for SPADs located at the centre of both wafers, and subsequently potential countermeasures for improved uniformity proposed. Arrays of multiple SPADs were then focused on, with AGR width having an impact on both single pixel SPADs and multiple pixel SPAD arrays, with improved homogeneity observed for the larger AGR widths. Finally, the research concludes with a proof-of-concept demonstration of a SPAD integrated with a low-loss waveguide chip as a hybrid detector chip, for use within an on-chip QKD system, operating at TEC-accessible temperatures and at a gated frequency of 1 GHz. At the time of writing, no reports of integrated SPADs for on-chip QKD have been demonstrated, making this the first time this type of single-photon detector has been used for on-chip QKD systems.
Degree
thesis:*- Name dc:type.qualificationname
- Doctor of Philosophy (PhD)
- Level dc:type.qualificationlevel
- Doctoral
- Grantor dc:publisher.institution
- University of Cambridge
- Year dc:date.issued
- 2023
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Scowen, Rosemary
- Advisor dc:contributor.advisor
-
- Ritchie, David
Subjects
dc:subject × 10Rights
dc:rightsIdentifiers
dc:identifier.*- DOI dc:identifier.doi
- https://doi.org/10.17863/CAM.109787
- OAI identifier oai:identifier
- oai:www.repository.cam.ac.uk:1810/370348