Oxidation of two-dimensional (2D) transition metal dichalcogenide crystals for future nano-electronic devices: Anisotropic reactivity and selectivity

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• Understanding and controlling the oxidation of 2D crystals is crucial for the development of 2D transistor technologies, as recent papers demonstrate the implementation of oxidized 2D materials as contacts and dielectric layers [3]. Interestingly, these anisotropic crystals with self-passivating basal planes exhibit unique reactivity and oxidation behavior, as revealed for monolayer-thin 2D crystals with micrometer-scale lateral dimensions (figure 1) [4,5]. However, significant knowledge gaps remain regarding the atomic-scale mechanisms governing oxidation of 2D heterostructures and their controlled implementation, especially in device-relevant structures with lateral dimensions below 100 nm. 
   
• This PhD research topic focuses on understanding and controlling the oxidation mechanisms of nanoscale heterostructures of 2D materials. We target selective, layer-by-layer oxidation with atomic-scale control of hetero-stacks formed with various 2D materials. We aim to explore and manipulate 2D crystals with varying lateral dimensions from the micrometer to nanometer scale, revealing insights into the impact of the exposed surface character. We will enrich the study of oxidation with subsequent dielectric or metal depositions, relevant for the fabrication of gate stacks and contacts (figure 1).

• You will start with a comprehensive literature overview. You will experimentally study the oxidation of 2D materials in the lab and in our 300 mm clean room. The 2D crystals and heterostructures will be obtained by state-of-the-art processes including metal organic chemical vapor deposition (MOCVD) [6]. Before and after oxidation, the samples will be characterized by complementary techniques to reveal insight in the initial oxidation and deposition stages at the nanoscale. The oxidation kinetics will be analyzed by analytical and/or numerical models [4,5]. One central topic is studying the selectivity of the oxidation of the 2D multilayer crystal while preserving a semiconducting monolayer. You will combine this study with our expertise on area-selective deposition of metals and dielectrics on 2D crystals [5]. The obtained insights in selective oxidation and deposition will contribute to the creation of 2D heterostacks with atomic scale control, ultimately enabling applications in devices and advanced test vehicles. 

• You will join imec’s Materials and Interfaces, Deposition and Analysis (MIDA) department and benefit from its strong expertise in thin film deposition and epitaxy [4,5,6,7]. Your PhD research will take place at the interface of science and industrial innovation, with access to imec’s state-of-the-art cleanroom and characterization labs. You will enrich your competences via the KU Leuven PhD trajectory and the imec academy. You will share your results with industrial partners and the international research community and be part of a vibrant MIDA PhD community of around 30 students supported by scientists, engineers, staff, and professors. The topic potentially includes international collaborations with other academic groups.

[1] K. S. Novoselov et al., Science, 353 (6298), 9439, 2016.

[2] K. P. O’Brien et al., in 2021 IEEE International Electron Devices Meeting (IEDM), Dec. 2021, p. 7.1.1-7.1.4.

[3] Ngo, T.D., et al, npj 2D Mater. Appl. (2026) doi: 10.1038/s41699-026-00728-8

[4] Hozaien, N., et al. , J. Vac. Sci. Technol. A 44, 052202 (2026) J. Vac. Sci. Technol. A 44, 052202 (2026)

[5] Ansh et al, . Adv. Funct. Mater. e16482 (2025) doi:10.1002/adfm.202516482.

[6] Kandybka. I. et al., ACS Nano, p. acsnano.3c09364, Jan. 2024, doi: 10.1021/acsnano.3c09364.

[7] Groven, B. et al., https://www.researchsquare.com/article/rs-4504047/v1