High-performance and Reliable Shortwave Infrared Image Sensor based on Colloidal Quantum Dots for 2D and 3D Imaging

Various technologies investigate the ability to sense and detect light in the shortwave infrared spectrum (SWIR, 1 µm<l<2.5 µm). Autonomous cars, smart agriculture, eye tracking for AR and VR applications, face recognition, surveillance, machine vision and new microscopy techniques can take advantage of additional information found in SWIR.

Colloidal quantum dots (CQD), as one of the emerging SWIR sensing technologies, offers cost-efficient and high-resolution imaging. III-V semiconductor-based CQDs are gaining attention due to their RoHS compliance and the potential for fast photodetection, offering an advantage over Pb- or Hg-containing CQDs. However, the performance and reliability of III-V CQDs still fall short. This project aims to understand and improve the signal-to-noise ratio, speed and stability of CQD SWIR photodetectors. The PhD will focus on understanding how the choice and treatments of photodetector stack layers, especially the CQDs regarding their chemical composition and ligand, influence their optical constants, mobility, dielectric constants, energetic levels, bulk and interface defects. With this information, a further understanding on the device performance is required, e.g. noise, carrier extraction efficiency, and speed. The PhD student will be involved in opto-electronic simulation, the fabrication of devices, current and capacitance-based measurements (I-V, C-V, C-f), spectral response measurements (absorption, EQE), as well as in-depth characterizations like photo electron spectroscopy measurements (UPS, XPS, HAXPES).

Ultimately, these photodetectors will be integrated into customized readout integrated circuits (ROICs) to enable 2D and 3D SWIR imaging.