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/Job opportunities/UltraFast colloidal quantum dot photodetectors for Time-of-Flight

UltraFast colloidal quantum dot photodetectors for Time-of-Flight

PhD - Leuven | More than two weeks ago

Range imaging with colloidal quantum dot photodetectors never worked this fast!


State-of-the-art range detection imagers use a silicon based Time-of-Flight (ToF) circuitry for pixel readout, in combination with a silicon absorber for the light detection. As a consequence, the usable wavelength range is limited to the absorption window of silicon. Most common ToF sensors employ infrared light with a wavelength range around 940nm. For increased ranging, near-infrared light with higher wavelengths are suggested, as they enable high power illumination in an eye-safe region. Using colloidal quantum dots as the absorbing material, the spectral range can be selected, ranging from visible over near-infrared to short-wave infrared. These characteristics are promising for future ToF image sensors with super-high resolution. We intend to integrate such novel thin photodetectors on silicon read-out chips.


The purpose of this PhD is to research thin-film devices for ultra-fast response in the near-infrared region. The thin-film semiconductors are deposited from solution using colloidal quantum dots (III-V or II-VI materials). The full stack will be defined by the optical and electrical properties of each layer, as well as the process limitations inherent to stacking of thin films. In depth characterization will be crucial to understand the response speed limitations of the stack and to demonstrate nano-second operation. A close collaboration with synthesis teams is required for feedback on the inherent speed limitations of the used quantum dots. This PhD therefore has two important pillars: 1) opto-electrical characterization of colloidal quantum dot photodiodes, and 2) process development to realize complex stacks with novel materials for the high-speed performance of photo-detection. The PhD student will be involved in the entire fabrication cycle (design, processing and characterization) performed in the state-of-the-art facilities including imec's cleanroom and dedicated thin-film labs.

The candidate

You are a highly motivated recent graduate holding a master’s degree in nano-engineering, physics, material science, electrical engineering, or related. You have an interest in the processing of thin-film semiconductors, optical effects in such layers, and electrical and optical characterization. You will be expected to work safely in a cleanroom environment and acquire processing and lab skills. It is expected that you will present results regularly.  You are a team player and have good communication skills as you will work in a multidisciplinary and multicultural team spanning several imec departments. Given the international character of imec, an excellent knowledge of English is a must.

Required background: nano-engineering, physics, materials science or electrical engineering with strong affinity for device physics

Type of work: 60% experimental 30% analysis and simulation 10% literature

Supervisor: Paul Heremans

Daily advisor: David Cheyns

The reference code for this position is 2021-101. Mention this reference code on your application form.