Elektromanyetik Alanlar ve Mikrodalga Tekniği Anabilim Dalı
Eskişehir Teknik Üniversitesi3
Arşivlenen Tez
0
DOI Atanmış
0%
DOI Oranı
Anabilim Dalı
Investigation of novel memristor-memtransistor devices for potential neuromorphic computing applications via alternative synthesis routes
As the need for faster and more efficient data processing grows particularly with the rise of artificial intelligence (AI) applications conventional Von Neumann architectures face fundamental limitations due to the separation of memory and processing units. Memristors and memtransistors offer a promising alternative by enabling unified memory-computation architectures and emulating key features of biological synapses, making them strong candidates for neuromorphic computing. In this context, two-dimensional (2D) materials, such as transition metal dichalcogenides (TMDs), stand out for their atomic thickness, electrostatic tunability, and defect engineering flexibility, all of which are critical for implementing low-power, high density, and scalable memristive devices. However, challenges remain in achieving stable and reproducible switching behavior, largely due to defect-driven mechanisms such as ion migration, phase transitions, and filamentary conduction. This thesis explores two experimental strategies to address these challenges using alternative fabrication methods. First, memtransistor structures based on monolayer MoS₂ were fabricated via chemical vapor deposition (CVD), and the effect of channel length on synaptic behavior and electrical performance was systematically investigated. The findings highlight how device geometry influences neuromorphic functionalities. Second, a novel fabrication route was developed for titanium-based memristors using plasma enhanced atomic layer deposition (PEALD). While full MXene formation is still under study, the resulting crystalline TiC phase was successfully integrated into a vertical memristor structure, exhibiting reliable resistive switching and short-term synaptic plasticity. Together, these results demonstrate the potential of 2D-material-based memristive systems for neuromorphic computing and provide insight into tunable, scalable, and CMOS-compatible fabrication routes.
Kablosuz metamalzemeden ilham alınan dönüş algılayıcıları
Recently steel construction structures have been attracting increasingly more attention due to the speed and ease of their construction. However, to detect potential damages in these structures, long-term and cost-effective health monitoring solutions are required. A rotation-based bending movement, which typically occurs in the load carrying elements of these structures (such as beams), is an example of the aforementioned potential damage. In this thesis, for measuring small bending rotations (10−4 ∼ 10−5 radians) in the structures made of materials such as steel, a novel wireless rotation sensing system with a high level of sensitivity and resolution is proposed and demonstrated. This system consists of two elements: an interrogating antenna and an interdigital double-layer sensor. The proposed sensing system operates based on the principle of near-field coupling between the antenna and the sensor. Briefly, by rotating one layer with respect to the other, the electromagnetic coupling between the layers changes and the resonance frequency is consequently shifted. This frequency shift can be recorded by tracking the resonance dips in the S11 response of the antenna. In the thesis work, various experiments were systematically performed to characterize the sensing system. A high rotation resolution of 20 µ-radians, an excellent sensitivity level of 28 MHz/degree, and a large dynamic range extending over 40◦ were measured. Furthermore, the validity of measurement results was verified by using full-wave electromagnetics simulator and applying digital image correlation (DIC) method for 2D measurements.
Alternatif j-sınıfı yaklaşımı ile GaN teknolojisi temelligeniş bant yüksek verimli güç yükselteci uygulamaları
RF power amplifiers have been the essential elements of any transmit/receive block. Especially in the transmit chain, some applications require high RF power, such as radar, jammer, telecommunication signals targeting a wide range of coverage. High power requirements in RF broadcast mean high supply power to feed RF PA. The efficiency parameter of a high-power transmission system becomes an issue due to heating problems and performance degradation depending on rising temperatures. The heating problem is commonly solved using active cooling plants. Cooling plants add extra cost demanding discrete power supplies and considerable amount of design labor. With these problems at hand, industrial and academic environments have turned to look for more efficient amplifier topologies. In this thesis, modified class-J schemes proposed to enhance operating bandwidth are studied. A modification called "normalized resistive-reactive class-J" (NRRCJ) approach is proposed. Detailed parametric analysis is presented. The effects of parameters in governing equations are discussed. A related engineering design procedure is demonstrated with an ultra-broadband GaN PA. Prototype PA operating at 400-3200 MHz capable of at least 10 W saturated output power is fabricated. Measured efficiency values of %53-%69.8 are obtained at saturated output power. The average efficiency is calculated as %62.45. The measurement results, theoretical aspects, and expectations are compared. It is shown that the resistive termination of harmonics in a systematic way makes it possible to achieve a broadband and relatively high efficiency performance, simultaneously. The final prototype achieves remarkable compatibility with a practical RF system, compared with similar examples in the literature, in terms of size, gain, efficiency, output power and operating frequency band.