Abstract
Graphene is an ideal candidate for next generation applications as a transparent electrode for electronics on plastic due to its flexibility and the conservation of electrical properties upon deformation. More importantly, its field-effect tunable carrier density, high mobility and saturation velocity make it an appealing choice as a channel material for field-effect transistors (FETs) for several potential applications. As an example, properly designed and scaled graphene FETs (Gr-FETs) can be used for flexible high frequency (RF) electronics or for high sensitivity chemical sensors. Miniaturized and flexible Gr-FET sensors would be highly advantageous for current sensors technology for in vivo and in situ applications. In this paper, we report a wafer-scale processing strategy to fabricate arrays of back-gated Gr-FETs on poly(ethylene naphthalate) (PEN) substrates. These devices present a large-area graphene channel fully exposed to the external environment, in order to be suitable for sensing applications, and the channel conductivity is efficiently modulated by a buried gate contact under a thin Al2O3 insulating film. In order to be compatible with the use of the PEN substrate, optimized deposition conditions of the Al2O3 film by plasma-enhanced atomic layer deposition (PE-ALD) at a low temperature (100 °C) have been developed without any relevant degradation of the final dielectric performance.
Highlights
One of the new challenges in the field of electronics is represented by flexible devices
In our experiments we developed a 100 °C plasma-enhanced atomic layer deposition (PE-Atomic layer deposition (ALD)) process using a PE ALD LL reactor by SENTECH Instruments GmbH, starting with trimethylaluminium (TMA) as a metal-organic chemical precursor and O2 as the oxygen source for the Al2O3 synthesis
The developed low temperature (LT) and prolonged cycle process was analyzed on a silicon (100) reference wafer and compared to a standard temperature (ST) PE-ALD growth process
Summary
One of the new challenges in the field of electronics is represented by flexible devices. In order to be compatible with the use of the PEN substrate, optimized deposition conditions of the Al2O3 film by plasma-enhanced atomic layer deposition (PE-ALD) at a low temperature (100 °C) have been developed without any relevant degradation of the final dielectric performance.
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