PRADO DA SILVA Gabriel
ORCID: 0000-0002-6522-0042
Ph.D. thesis: Atomic/Molecular Layer Deposition of two-dimensional vanadium sulfides (VSx) films for electrical contacts on 2D-MoS2 based logic devices.
Context: Semiconducting two-dimensional transition metal dichalcogenides (2D-TMDs), such as MoS2, have witnessed a surge in popularity over the past decade, providing novel perspectives for the fabrication of ultra-downscaled electronic devices. However, contact engineering on MoS2 remains challenging due to the high contact resistance exhibited by most metals and the damage that is induced at the metal/TMD interface. In this regard, the utilization of metallic TMDs, such as VS2, emerges as a promising solution for the establishment of efficient and industrially applicable contacts on 2D-TMDs [1] [2].Thus, the use of conformal and self-limiting techniques - such as ALD - are of great interest for the deposition of VSx contacts in order to ensure a continuous coating of the contact hole in any device architecture. However, the atomic layer deposition of VS2 has been the subject of only a limited number of investigations, in part due to the difficulty of stabilizing the +4 valence of vanadium in the V-S system [4] [5].
Objective: The aim of this thesis is to gain insight into the mechanisms of growth and decomposition that occur during the deposition and crystallization of vanadium sulfides (VSx) ultrathin films on MoS2/SiO2 substrates, using the one-of-a-kind ALD/MLD reactor of the LMGP, which allow the synthesis to be monitored and controlled by in-situ ellipsometry, residual gas analysis and in situ x-ray studies. These in situ measumerents are coupled with ex situ, post-synthesis analysis.
Characterization techniques:
- In situ techniques: ellipsometry and residual gas analysis at LMGP. In situ synchrotron studies at the beamline SIRIUS of the SOLEIL synchrotron facility, which is optimized for performing grazing incidence X-ray fluorescence (XRF), X-ray absorption spectroscopy (XAS), and X-ray reflectivity (XRR) and X-ray diffraction (XRD).
- Ex situ techniques: Raman micro-spectroscopy, ARXPS (Angle Resolved X-ray Photoelectron Spectroscopy), SIMS (Secondary Ion Mass Spectrometry) and TEM (Transmission Electron Microscopy) at CEA-Leti/PFNC. Conventional XPS will be complemented by the use of a novel lab-based hard X-ray source (HAXPES), which will facilitate the investigation of the chemical composition at the dichalcogenides surface and the in-depth distribution of sulfur within the VSx layer.
To find out more about SOLEIL synchrotron facility
To find out more about Labex Microelectronics
References:
[1] Nat Commun (2023). 10.1038/s41467-023-41779-5; [2] Nature (2021). 10.1038/s41586-021-03472-9; [3] Nano Letters (2017). 10.1021/acs.nanolett.7b01914; [4] Adv. Funct. Mater. (2022). 10.1002/adfm.202204760; [5] ACS Nano (2024). 10.1021/acsnano.3c05907
Activités / CV
EXPERIENCES
• 10/2024 - present: LMGP & CEA-Leti - Ph.D. student (Grenoble, France).
Thesis director: H. Renevier (LMGP). Co-supervisors: S. Cadot (CEA-Leti) and N. Gauthier (CEA-Leti).
Ph.D. thesis: Atomic/Molecular Layer Deposition of two-dimensional vanadium sulfides (VSx) films for electrical contacts on 2D-MoS2 based logic devices.
• 02/2024 - 08/2024: Safran Aerosystems - Materials & Processes Intern (Roche-La-Molière, France).
Subject: Replacement of surface treatments affected by the REACH regulation (Master's Degree Final Project - Projet de Fin d'Etudes).
Results: The development and industrial validation of innovative Cr(VI)-free surface treatments for aluminum alloys have been undertaken, with the objective of providing corrosion protection, electrical conductivity, and paint adhesion for aircraft fuel system components. These novel processes are in accordance with the REACH regulation of the European Chemicals Agency (ECHA), reducing significantly the risks to operators' health and the environment compared to classical surface treatments, representing a significant step towards a sustainable aviation industry.
• 10/2021 - 07/2022: Laboratory of Applied Nanomaterials, UTFPR Londrina campus - Volunteer researcher (Londrina, Brazil).
Subject: Synthesis and characterization of nanocomposites based on silver nanowires in a polymeric matrix (Scientific Initiation Project).
Results: In this study, a cost-effective, flexible, transparent, and electrically conductive composite was synthesized using a spray-coating method with silver nanowires in a polydimethylsiloxane (PDMS) matrix.
EDUCATION
• 2024 - present: Université Grenoble Alpes - UGA, Ph.D. in Materials Physics (Grenoble, France).
• 2022 - 2024: Ecole Nationale d'Ingénieurs de Tarbes - ENIT-UTTOP, Master's Degree in General Engineering - specialized in Materials & Processes (Tarbes, France).
• 2018 - 2024: Universidade Tecnológica Federal do Paraná - UTFPR, Bachelor's Degree in Materials Engineering (Londrina campus, Brazil).
• 2014 - 2017: Universidade Tecnológica Federal do Paraná - UTFPR, I.T. Technical Course (Campo Mourao campus, Brazil).
LANGUAGES
• Portuguese: native.
• French: bilingual.
• English: advanced.
• Spanish: beginner.