In space applications such as earth observation missions, one of the main contributor to image degradation remains space radiations. Indeed, the image sensor is exposed to cumulative effects coming from incident particles (such as protons), that will progressively affect the image quality. In particular, one effect of the dark current (signal that remains when there is no incident light) becomes predominant and prevents calibration to be correctly performed. This parasitic signal is called Dark Current Random Telegraph Signal (DC-RTS): for a given pixel, this corresponds to a signal that switches randomly between discrete level with time. Practically, this looks like “blinking pixels”.

The main impact of such kind of signal corresponds to the error in calibration: the useful is obtained thanks to the subtraction of the measured signal by the dark current. If this dark current is not stable and switches between several values (that can be separated by up to several order of magnitude), the useful signal is no more reliable. This will cause a degradation of the image quality all along the mission. This kind of signal has become one of the critical impact for recent space programs. 

In the literature, DC-RTS is attributed to defects in the crystalline structure of semiconductors devices that introduce energy levels in the bandgap. It has already been observed in a wide range of semiconductor types (Silicon, InGaAs, HgCdTe, InSb, …). Signatures of different defects kinds have been extracted and analyzed according to the incident particle. However, the mechanism is not yet fully understood. The main hypothesis is a metastable defect that would switch randomly between several states leading to jumps in the generated current (metastable center).   

In parallel some ab-initio simulations from the impact of a particle in a semiconductor have been realized in order to understand mechanisms in the crystalline structure: creation of defects, and their behavior from nanosecond after the impact to several hours.  

More recently, it has been shown that point defects may induce random telegraph signal. This has never been underlined before become other contributions were hiding this effect.

The objective of this PhD is to understand and identify the defects responsible thanks to simulations and measurements on irradiated Silicon detectors. 

More precisely, the candidate will have to: 

• Perform a comprehensive review of the state-of-the-art research and technology about:

 - the different CMOS technologies used for imaging purposes

- radiation effects on semiconductor devices

 - defects creation in the crystalline structure 

- ab-initio modeling and particle-matter interaction

- the existing methods and proposed models for RTS mechanism

• Model and simulate DC-RTS from existing works to experimental observations

• Realize DC-RTS measurements on several irradiated devices to illustrate simulations 

• Identify defects created by different kind of irradiation (ionizing effects or displacement damage effect) thanks to simulations and observations 

• Understand the different signatures obtained for the different types of radiations

• Make a synthesis of the work and propose guidelines to mitigate the impact of radiations on semiconductor devices

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For more Information about the topics and the co-financial partner (found by the lab!); contact Directeur de thèse - vincent.goiffon@isae-supaero.fr

Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online before March 13th, 2026 Midnight Paris time!

Master Degree or equivalent (e.g. French Engineering School Degree) specialized in nano/microelectronics (design, process, ...) / optoelectronics / imaging electronics, sensors, detectors / semiconductor physics / solid-state physics / analog and digital electronics