Élaboration et intégration du VO2 pour la réalisation de diodes photoniques infrarouges dédiées à la thermotronique
Bibliographic record
Abstract
Modern information processing relies predominantly on the manipulation of electrical currents and voltages, a foundation established through decades of progress in the microelectronics industry. In contrast, thermotronics, the emerging field of thermal information processing, remains in its infancy. Despite its technological potential, thermotronics lacks the fundamental components and effective mechanisms to guide, amplify, or modulate heat.Radiative thermal transistors and diodes, which modulate heat through photon-mediated energy transfer, offer a promising approach to overcoming this limitation. Central to such devices is vanadium dioxide (VO₂), a phase-change material that undergoes a reversible metal-insulator transition (MIT) near 70 °C, accompanied by a significant change in optical properties within the mid-infrared range. To achieve compatibility with existing microelectronic technologies, integrating VO₂ onto a silicon platform is essential. However, challenges such as lattice mismatch and the formation of interfacial oxides and silicates compromise film quality and device performance, leading to reliability issues.This thesis presents a comprehensive investigation into the development, optimization, and integration of VO₂ thin films for radiative thermal photonic applications. The initial stage focused on heteroepitaxial growth of VO₂ on various sapphire orientations in order to benchmark crystal quality, grain structure, and strain behavior. The findings revealed strong correlations between substrate orientation, strain, and phase-transition characteristics, offering critical insights into growth dynamics and transport properties.Building upon these results, VO₂ was integrated on a silicon platform using a CMOS-compatible HfₓZr₁₋ₓO₂ (HZO) buffer layer. This strategy enhanced the amplitude and sharpness of the MIT behavior of VO₂, while significantly reducing thermal hysteresis and suppressing grain-boundary defects. Additionally, the study identified the presence of the intermediate M2 phase using temperature-dependent X-ray diffraction and infrared spectroscopy and correlated it to the M2 phase of VO₂.The research then progressed to integrating VO₂ into suspended membrane structures on a MEMS bolometer platform for radiative diode applications. Key fabrication challenges, including film delamination, membrane thinning, and microloading effects, were addressed through architectural redesigns and process optimizations. Although full membrane release was not achieved within this work, these advancements mark a significant step forward from material-level development to functional device implementation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".