Search results for "Transistor"
showing 10 items of 234 documents
Controlling the mode of operation of organic transistors through side chain engineering
2016
Electrolyte-gated organic transistors offer low bias operation facilitated by direct contact of the transistor channel with an electrolyte. Their operation mode is generally defined by the dimensionality of charge transport, where a field-effect transistor allows for electrostatic charge accumulation at the electrolyte/semiconductor interface, whereas an organic electrochemical transistor (OECT) facilitates penetration of ions into the bulk of the channel, considered a slow process, leading to volumetric doping and electronic transport. Conducting polymer OECTs allow for fast switching and high currents through incorporation of excess, hygroscopic ionic phases, but operate in depletion mode…
Aqueous electrolyte-gated ZnO transistors for environmental and biological sensing
2014
Electrolyte-gated transistors (EGTs) based on ZnO thin films, obtained by solution processing of suspensions of nanoparticles, have a low turn-on voltage (<0.5 V), a high on/off ratio and transconductance exceeding 0.2 mS. Importantly, the ZnO surface can be functionalized with a large variety of molecular recognition elements, making these devices ideal transducers in physiological and environmental monitoring. We present simple glucose-sensing and ion-selective EGTs, demonstrating the versatility of such devices in biosensing.
Assessing Radiation Hardness of SIC MOS Structures
2018
It is widely known that devices based on wide gap semiconductors show potential benefits in terms of saving mass, increasing power densities compared with standard Silicon ones [1]. The higher operating temperatures these components can withstand can also reduce the power budget currently used for cooling down power electronics. These factors are critical in space applications where, for example SiC devices are very promising. However, in this field reliability is a paramount requirement, and radiation conditions can compromise the usage of these new technologies.
Current-Driven Organic Electrochemical Transistors for Monitoring Cell Layer Integrity with Enhanced Sensitivity
2021
In this progress report an overview is given on the use of the organic electrochemical transistor (OECT) as a biosensor for impedance sensing of cell layers. The transient OECT current can be used to detect changes in the impedance of the cell layer, as shown by Jimison et al. To circumvent the application of a high gate bias and preventing electrolysis of the electrolyte, in case of small impedance variations, an alternative measuring technique based on an OECT in a current-driven configuration is developed. The ion-sensitivity is larger than 1200 mV V-1 dec-1 at low operating voltage. It can be even further enhanced using an OECT based complementary amplifier, which consists of a p-type a…
Monitoring of Cell Layer Integrity with a Current-Driven Organic Electrochemical Transistor
2019
Abstract The integrity of CaCo-2 cell barriers is investigated by organic electrochemical transistors (OECTs) in a current-driven configuration. Ion transport through cellular barriers via the paracellular pathway is modulated by tight junctions between adjacent cells. Rupturing its integrity by H2O2 is monitored by the change of the output voltage in the transfer characteristics. It is demonstrated that by operating the OECT in a current-driven configuration, the sensitive and temporal resolution for monitoring the cell barrier integrity is strongly enhanced as compared to the OECT transient response measurement. As a result, current-driven OECTs are useful tools to assess dynamic and crit…
Ambipolar MoS2 Transistors by Nanoscale Tailoring of Schottky Barrier Using Oxygen Plasma Functionalization
2017
One of the main challenges to exploit molybdenum disulfide (MoS2) potentialities for the next-generation complementary metal oxide semiconductor (CMOS) technology is the realization of p-type or ambipolar field-effect transistors (FETs). Hole transport in MoS2 FETs is typically hampered by the high Schottky barrier height (SBH) for holes at source/drain contacts, due to the Fermi level pinning close to the conduction band. In this work, we show that the SBH of multilayer MoS2 surface can be tailored at nanoscale using soft O-2 plasma treatments. The morphological, chemical, and electrical modifications of MoS2 surface under different plasma conditions were investigated by several microscopi…
Impact of Gamma Radiation on Dynamic RDSON Characteristics in AlGaN/GaN Power HEMTs
2019
GaN high-electron-mobility transistors (HEMTs) are promising next-generation devices in the power electronics field which can coexist with silicon semiconductors, mainly in some radiation-intensive environments, such as power space converters, where high frequencies and voltages are also needed. Its wide band gap (WBG), large breakdown electric field, and thermal stability improve actual silicon performances. However, at the moment, GaN HEMT technology suffers from some reliability issues, one of the more relevant of which is the dynamic on-state resistance (R) regarding power switching converter applications. In this study, we focused on the drain-to-source on-resistance (R) characteristic…
Evaluation of Gallium Nitride Transistors in Electronic Power Conditioners for TWTAs
2015
The aim of this paper is to evaluate the benefits of replacing Si Mosfets transistors with enhancement mode GaN transistors in a Half-Bridge Zero Voltage and Zero Current Switching Power Switching Converter (ZVZCPS). This converter is usually used as power supply of the travelling-wave tube amplifiers (TWTAs) in aerospace applications. In this paper, firstly the converter is theoretically analyzed, obtaining its operation, losses and efficiency equations, these equations are used to obtain optimizations maps based on the main system parameters. In this way, the ideal design parameters can be visually obtained. These optimization maps are the key to quantify the potential benefits of GaN tra…
High-Speed Memory from Carbon Nanotube Field-Effect Transistors with High-κ Gate Dielectric
2009
We demonstrate 100 ns write/erase speed of single-walled carbon nanotube field-effect transistor (SWCNT-FET) memory elements. With this high operation speed, SWCNT-FET memory elements can compete with state of the art commercial Flash memories in this figure of merit. The endurance of the memory elements is shown to exceed 104 cycles. The SWCNT-FETs have atomic layer deposited hafnium oxide as a gate dielectric, and the devices are passivated by another hafnium oxide layer in order to reduce surface chemistry effects. We discuss a model where the hafnium oxide has defect states situated above, but close in energy to, the band gap of the SWCNT. The fast and efficient charging and discharging…
Effect of humidity on the hysteresis of single walled carbon nanotube field-effect transistors
2008
Single walled carbon nanotube field-effedt transistores (SWCNT FETs) are attributed as possible building blocks for future molecular electronics. But often these transistors seem to randomly display hysteresis in their transfer characteristics. One reason for this is suggested to be water molecules adsorbed to the surface of the gate dielectric in this study we investigate the thysteresis of SWCNT FETs at different relative humidities. We find that SWCNT FETs having atomic layer deposited (ALD) Hf0 2 -Ti0 2 .- Hf0 2 as a gate dielectric retain their. ambient condition hysteresis better in dry N2 environment than the more commonly used SiO 2 gate oxide.