Advanced physical sensors based on carbon nanotube/polydimethylsiloxane (CNT/PDMS) nanocomposites have recently attracted much attention for potential applications such as wearable and flexible electronic devices. In this work, a CNT/PDMS sponge was fabricated and their capacitive as well as resistive response was investigated by impedance characterization with an equivalent circuit model. The newly defined gauge factor, which considers simultaneously both the piezocapacitive and piezoresistive effects of CNT/PDMS sponge sensors, showed a significantly improved sensitivity. This work provides important information for a better understanding of CNT/PDMS nanocomposites and their sensing performance.
Low voltage operational organic transistors (< 4 V) based on pentacene were successfully fabricated with hybrid dielectric films composed of aluminum oxide using atomic layer deposition and various phosphonic acid-based self-assembled monolayers as the gate dielectrics. High capacitances up to 279 nF/cm2, low leakage current densities of 10−8 A/cm2 at 6 V, and high breakdown fields up to 7.5 MV/cm were obtained. The transistors with the octadecylphosphonic acid hybrid dielectric exhibited an improved saturation mobility of 0.58 cm2/Vs, a subthreshold slope of 151 mV/decade, a threshold voltage of − 1.84 V and an on–off current ratio of 106. The low surface energies of the self-assembled monolayers having non-polar terminal groups, such as methyl and pentafluorophenoxy, improved the carrier conduction of the transistors due to the pentacene growth with an edge-on orientation for low voltage operation. The pentafluorophenoxy end-group showed an accumulation of holes at the semiconductor-dielectric interface.
3 September 2020 in ACS Applied Materials & Interfaces
AlGaN/GaN high electron mobility transistors (HEMTs) possess excellent electrical and thermal properties. In this study, we examined the electrical performance of AlGaN/GaN HEMTs to clarify the operational mechanism of the device with temperature variation in an effort to further advance development of high-speed, high-power devices and sensors for temperature applications. Our results revealed drain current degradation caused by temperature-dependent series resistance, as well as several scattering mechanisms. In addition, a negligible surface roughness scattering effect in AlGaN/GaN HEMTs was confirmed through mobility attenuation factors.
Electrical performance and transport mechanisms in 2-D transition-metal dichalcogenide materials should be investigated under a range of electrical parameters for practical application. In this paper, partially depleted (PD) molybdenum disulfide (MoS 2 ) transistors were fabricated with a thick flake mechanically exfoliated from bulk crystals, and their operating mechanism is discussed considering the gate-uncontrollable conduction channel, the maximum depletion width (D max ), and the impact of series resistance (R sd ). In addition, the intrinsic mobility of a neutral bulk channel in PD-MoS 2 transistors was extracted from the simply separated gate-controllable drain current with a depletion approximation.