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Communication Dans Un Congrès Année : 2023

Thermal information processing using phase change materials

Résumé

Industrial waste heat in the EU is estimated about 300TWh/year. This freely available energy remains unharvested. With radiative thermal devices, it could in contrary power internet of things. Unlike its electronic counterparts, thermal information processing (thermotronics) via radiative heat flow and temperature control is a nascent technology. To achieve this goal, a thermal transistor has been proposed1. It consists of a membrane of a material undergoing a metal-insulator transition (MIT), e.g. VO2, which acts as the gate between two thermal reservoirs (source and drain), e.g. SiO2. VO2 undergoes a structural phase transformation (SPT) at approximately 70°C from insulating monoclinic structure at room temperature to metallic rutile. The two crystallographic structures have large variation in their complex refractive index in the mid-IR frequency range. To keep with the current trends of microelectronic industry, it is imperative to integrate VO2 on Si. However, the higher lattice mismatch and formation of oxides and silicates at the interface between VO2 and crystalline Si degrade the quality and functionality of VO2 film. Additionally, VO2(M1) is a challenging material to integrate into patterned heterostructures because it can exist not only as multiple polymorphs (A, B, M1) but the high temperature depositions can lead to formation of various oxidation states phases that are present in the V-O system (VnO2n-1, VnO2n+1). This work was conducted to study the growth of VO2 on silicon with oxide buffer layers using RF magnetron sputtering of a V2O5 ceramic target in argon atmosphere. We studied the structure-property relationships, specifically electrical and optical properties as a function of temperature across the Tc. Structural and compositional characterization are carried out using x-ray diffraction (XRD), atomic force microscopy (AFM), and x-ray photoemission spectroscopy (XPS) respectively; optical responses are studied using FTIR and electrical characterizations are performed using the four-point probe method. With the use of a very thin metal oxide buffer layer between silicon substrate and VO2 film, we demonstrate a high resistivity ratio (3 orders of magnitude between the two phases) and investigate the scope of improvement. The results show the influence of substrates temperature, VO2 grain size and strain on the amplitude of transition as well as the crystal structure of buffer layer on the structural and physical properties of interfaces and film morphology which subsequently affect the electrical bistability of VO2. The preliminary findings mentioned here are being utilized to improve the electrical bistability, thus allowing us to improve the reproducibility in operational modes of thermotronic devices.
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Dates et versions

hal-04216385 , version 1 (24-09-2023)

Identifiants

  • HAL Id : hal-04216385 , version 1

Citer

Swayam Sahoo, Anne Lamirand, Infante Ingrid C., Victor Pierron, Laurence Méchin, et al.. Thermal information processing using phase change materials. EMRS 2023 Fall Meeting, symposium T, European Materials Research Society, Sep 2023, Warsaw (Poland), Poland. ⟨hal-04216385⟩
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