Development of ligand exchange and coating strategies for the colloidal quantum dot based high resolution short-wave infrared imaging sensors

Date

2024-6

Author

Uzun, Batuhan

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InGaAs is still in use due to its high sensitivity for Short-Wave Infrared (SWIR) imaging sensor technology. However, InGaAs has disadvantages such as high production and raw material costs and long production conditions, as well as the problems encountered during the hybridization process. Limited resources are also an obstacle to the development of areas such as the automotive and defense industries where such sensors are needed. In this respect, sensors based on PbS colloidal quantum dots are considered the best material candidates as an alternative to InGaAs. PbS colloidal quantum dots can be easily produced monolithically on a chip at a low cost. However, the PbS quantum dot layer needs to go through many post-synthesis steps. Yet, the recently introduced direct synthesis method allows one-step PbS CQD ink synthesis which eliminates complex ligand exchange steps. Despite its infantile stage, with slight optimizations, the photodiodes that reached 1013 Jones detectivities in the IR region were produced in this thesis. Moreover, the low dark current density around 10-8 mA.cm-2 and fast rise/fall time (1.65/8.08 µs) were achieved. In addition to these promising photodetector performance parameters achieved by increasing the v quantum dot quality, production costs were also reduced with the optimization studies at the synthesis stage. In this context, the production yield of QDs increased by 42%. Furthermore, a detailed SCAPS study was conducted, and the optimal device architecture was identified. Moreover, a numerical comparison between p type and n-type inks revealed that the p-type ink could lead to a better device performance.

Subject Keywords

Colloidal quantum dot, Ligand exchange, Photodetector, Short-wave infrared imaging sensor

URI

https://hdl.handle.net/11511/110159

Collections

Graduate School of Natural and Applied Sciences, Thesis