Thin-Film Photodetector Optimization for Spectral Sensing and Imaging in Short-Wave Infrared

In recent years, there has been a significant increase in the integration of infrared image sensors in many everyday use devices such as smartphones and laptops, driven by the need for biometric sensors such as face recognition and fingerprint scanners. At the same time, a variety of new applications such as self-driving cars, augmented reality (AR) and virtual reality (VR) can take advantage of developments in the infrared imaging technology. Specifically, a growing demand exists for sensing technologies in the short-wave-infrared (SWIR), which relates to wavelengths in the range of 1µm-2µm. Nowadays, the available technologies for IR sensors is rather limited. Silicon can only detect in the near-infrared range (NIR) with a strong cut-off after 900 nm and the III-V semiconductors that are used for SWIR spectrum are having constraints in terms of throughput, resolution and high cost.  

Colloidal quantum dots (QDs) offer an alternative approach in detecting infrared light. Taking advantage of the quantum confinement, QDs, depending on their size can be tuned to detect different spectra from visible up to the NIR and SWIR. Furthermore, they can be deposited from solution over large area with low cost techniques such as spin coating.  

Our group has been developing SWIR image sensors based on QDs for the last 7+ years, combining expertise from several domains including material science, semiconductors, micro/nano fabrication, photonics and others. One of our latest endeavors is to integrate optical filters onto QD photodetectors with a goal of enabling affordable SWIR spectral sensors and imagers, targeting various applications in medicine, automotive industry, agriculture and machine vision. To achieve this, we have patented a new type of photodetector based on nanophotonics that combines photodetection and optical filtering in a single integrated device. The student will focus on electrical and optical co-optimization of these new photodetectors, with a focus on experimental work including fabrication and characterization. He/she will receive training on the relevant processing and characterization tools. After a short introduction to the facilities, an independent investigation is expected with the focus on short-term research goals.