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Projeto de investigação
TCAD simulation platform for oxide transistors and memories
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Low-temperature amorphous oxide semiconductors for thin-film transistors and memristors: physical insights and applications
Publication . Martins, Jorge de Souto; Barquinha, Pedro; Kiazadeh, Asal; Goes, João
While amorphous oxides semiconductors (AOS), namely InGaZnO (IGZO), have found market application in the display industry, their disruptive properties permit to envisage for more advanced concepts such as System-on-Panel (SoP) in which AOS devices could be used for addressing (and readout) of sensors and displays, for communication, and even for memory as oxide memristors are candidates for the next-generation memories. This work concerns the application of AOS for these applications considering the low thermal budgets (< 180 °C) required for flexible, low cost and alternative substrates. For maintaining low driving voltages, a sputtered multicomponent/multi-layered high-κ dielectric (Ta2O5+SiO2) was developed for low temperature IGZO TFTs which permitted high performance without sacrificing reliability and stability. Devices’ performance under temperature was investigated and the bias and temperature dependent mobility was modelled and included in TCAD simulation. Even for IGZO compositions yielding very high thermal activation, circuit topologies for counteracting both this and the bias stress effect were suggested. Channel length scaling of the devices was investigated, showing that operation for radio frequency identification (RFID) can be achieved without significant performance deterioration from short channel effects, which are attenuated by the high-κ dielectric, as is shown in TCAD simulation. The applicability of these devices in SoP is then exemplified by suggesting a large area flexible radiation sensing system with on-chip clock-generation, sensor matrix addressing and signal read-out, performed by the IGZO TFTs. Application for paper electronics was also shown, in which TCAD simulation was used to investigate on the unconventional floating gate structure. AOS memristors are also presented, with two distinct operation modes that could be envisaged for data storage or for synaptic applications. Employing typical TFT methodologies and materials, these are ease to integrate in oxide SoP architectures.
Foldable and Recyclable Iontronic Cellulose Nanopaper for Low-Power Paper Electronics
Publication . Cunha, Inês; Ferreira, Sofia Henriques; Martins, Jorge; Fortunato, Elvira; Gaspar, Diana; Martins, Rodrigo; Pereira, Luís; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; John Wiley and Sons Inc.
An increase in the demand for the next generation of “Internet-of-Things” (IoT) has motivated efforts to develop flexible and affordable smart electronic systems, in line with sustainable development and carbon neutrality. Cellulose holds the potential to fulfil such demands as a low-cost green material due to its abundant and renewable nature and tunable properties. Here, a cellulose-based ionic conductive substrate compatible with printing techniques that combines the mechanical robustness, thermal resistance and surface smoothness of cellulose nanofibrils nanopaper with the high capacitance of a regenerated cellulose hydrogel electrolyte, is reported. Fully screen-printed electrolyte-gated transistors and universal logic gates are demonstrated using the engineered ionic conductive nanopaper and zinc oxide nanoplates as the semiconductor layer. The devices exhibit low-voltage operation (<3 V), and remarkable mechanical endurance under outward folding due to the combination of the robustness of the nanopaper and the compliance of the semiconductor layer provided by the ZnO nanoplates. The printed devices and the ion-conductive nanopaper can be efficiently recycled to fabricate new devices, which is compatible with the circular economy concept.
Healable Cellulose Iontronic Hydrogel Stickers for Sustainable Electronics on Paper
Publication . Cunha, Inês; Martins, Jorge; Gaspar, Diana; Bahubalindruni, Pydi Ganga; Fortunato, Elvira; Martins, Rodrigo; Pereira, Luís; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; Wiley
Novel nature-based engineered functional materials combined with sustainable and economically efficient processes are among the great challenges for the future of mankind. In this context, this work presents a new generation of versatile flexible and highly conformable regenerated cellulose hydrogel electrolytes with high ionic conductivity and self-healing ability, capable of being (re)used in electrical and electrochemical devices. They can be provided in the form of stickers and easily applied as gate dielectric onto flexible indium–gallium–zinc oxide transistors, decreasing the manufacturing complexity. Flexible and low-voltage (<2.5 V) circuits can be handwritten on-demand on paper transistors for patterning of conductive/resistive lines. This user-friendly and simplified manufacturing approach holds potential for fast production of low-cost, portable, disposable/recyclable, and low-power ion-controlled electronics on paper, making it attractive for application in sensors and concepts such as the “Internet-on-Things.”.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
OE
Número da atribuição
SFRH/BD/122286/2016