Correlative Atom Probe Tomography and Electron Tomography for 3D Sub-Nanometer Analysis of InGaN-based Nano-Emitters Apply now

A PhD opportunity is available at CEA-LETI and PHELIQS Laboratory at CEA-IRIG, focusing on the development of advanced 3D structural and chemical characterization techniques for InGaN quantum dots. The research aims to integrate electron tomography (ET) and atom probe tomography (APT) to correlate structural and chemical features with device performance in photonic devices. The selected candidate will engage in cutting-edge work on the miniaturization of nitride light emitters and detectors, receive extensive training in semiconductor growth, 3D analysis, and advanced simulation techniques, and contribute to pioneering advancements in full-color all-nitride displays.

Context:  III-nitride semiconductors are the materials of choice for optoelectronics in the blue and green spectral ranges, and recent results in the red are promising for the development of full-color all-nitride displays. Research into the extreme miniaturization of nitride light emitters and detectors is driven by the pursuit of improved performance, energy efficiency, integration capabilities, and the opening of new technological frontiers. The progress towards nano-devices is linked to the evolution of sophisticated 3D characterization techniques at the sub-nanometer scale. The 3D chemical and morphological representation of InGaN QDs and the P-N doping distribution can be achieved by using (i) electron tomography (ET) in scanning transmission electron microscopy (STEM) mode for morphological information with a sub-nanometre spatial resolution, and (ii) atom probe tomography (APT) for chemical information with near-atomic spatial resolution and a low limit detection of ~5e18 cm-3 (the Mott transition occurs at 1e19 cm-3 in GaN, which is clearly resolved by APT).

Required work: The targets of this thesis are (i) the development of 3D structural and chemical characterization tools based on the coupling of ET and APT, and (ii) the application of this tools to photonic devices based on InGaN quantum dots, to obtain a correlation between structural/chemical features and device performance.

The student will participate to the growth of new technological structures based on InGaN quantum dots emitting in the visible range by plasma-assisted molecular-beam epitaxy. She/he will be trained on ET (in imaging mode) and APT, with the associated sample preparation techniques. She/he will set up a workflow for the experimental and numerical correlation between APT and ET analyses on the same specimen. APT density correction and deep learning approaches will be developed for the correction of APT artefacts and denoising/super-resolution of ET volumes. Finally, she/he will be trained on the use of a Schrodinger-Poisson solver for 3D simulations of the electronic band structure of InGaN QDs.

The PhD student will integrate two laboratories, namely CEA-LETI and the PHELIQS Laboratory at CEA-IRIG. At PHELIQS, she/he will be trained by experts on semiconductor growth and electronic simulations of III-N nanostructures. At the platform of nanocharacterization (PFNC), she/he will have access to state-of-the art transmission electron microscopes (TEM) suitable for the 3D analysis of beam-sensitive materials (this is the case for InGaN-based nanostructures), and will be trained on various commercial and open source packages dedicated to electron tomography. In addition, CEA-LETI has access to the last generation of APT.

https://www.pheliqs.fr/

https://www.leti-cea.fr/

https://www.minatec.org/en/research/minatec-dedicated-research-platforms/nanocharacterization-platform-pfnc/

Master degree or equivalent in Physics or Engineering.

Strong motivation for hands-on experimental work in nanotechnology and advanced characterization techniques.

Ability to work effectively in a collaborative, multidisciplinary team environment.