Search results for " Dielectric"
showing 10 items of 67 documents
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.
Hot carrier effects in n-MOSFETs with SiO2/HfO2/HfSiO gate stack and TaN metal gate
2009
Charge trapping and trap generation in field-effect transistors with SiO2/HfO2/HfSiO gate stack and TaN metal gate electrode are investigated under uniform and non-uniform charge injection along the channel. Compared to constant voltage stress (CVS), hot carrier stress (HCS) exhibits more severe degradation in transconductance and subthreshold swing. By applying a detrapping bias, it is demonstrated that charge trapping induced degradation is reversible during CVS, while the damage is permanent for hot carrier injection case. © 2008 Elsevier B.V. All rights reserved.
High-Yield of Memory Elements from Carbon Nanotube Field-Effect Transistors with Atomic Layer Deposited Gate Dielectric
2008
Carbon nanotube field-effect transistors (CNT FETs) have been proposed as possible building blocks for future nano-electronics. But a challenge with CNT FETs is that they appear to randomly display varying amounts of hysteresis in their transfer characteristics. The hysteresis is often attributed to charge trapping in the dielectric layer between the nanotube and the gate. This study includes 94 CNT FET samples, providing an unprecedented basis for statistics on the hysteresis seen in five different CNT-gate configurations. We find that the memory effect can be controlled by carefully designing the gate dielectric in nm-thin layers. By using atomic layer depositions (ALD) of HfO$_{2}$ and T…
Ultra-Low Noise Multiwalled Carbon Nanotube Transistors
2013
We report an experimental noise study of intermediate sized quasi ballistic semiconducting multiwalled carbon nanotube (IS-MWCNT) devices. The noise is two orders of magnitude lower than in singlewalled nanotubes (SWCNTs) and has no length dependence within the studied range. In these channel limited devices with small or negligible Schottky barriers the noise is shown to originate from the intrinsic potential fluctuations of charge traps in the gate dielectric. The gate dependence of normalized noise can be explained better using ballistic the charge noise model rather than diffusive McWhorter’s model. The results indicate that the noise properties of IS-MWCNTs are closer to SWCNTs than th…
Semi-Empirical Model for SEGR Prediction
2013
The underlying physical mechanisms in single event gate rupture (SEGR) are not known precisely. SEGR is expected to occur when the energy deposition due to a heavy ion strike exceeds a certain threshold simultaneously with sufficient electric field across the gate dielectric. Typically the energy deposition is described by using the linear energy transfer (LET) of the given ion. Previously the LET has been demonstrated not to describe the SEGR sufficiently. The work presented here introduces a semi-empirical model for the SEGR prediction based on statistical variations in the energy deposition which are described theoretically.
Organic Thin-Film Transistors with Enhanced Sensing Capabilities
2009
Organic thin-film transistors, used as sensing devices, have been attracting quite a considerable interest lately as they offer advantages such as multi parameter behaviour and possibility to be quite easily molecularly tuned for the detection of specific analytes. Here, a study on the dependences of the devices responses on important parameters such as the active layer thickness and its morphology as well as on the transistor channel length is presented. To introduce the least number of variables the system chosen for this study is quite a simple and well assessed one being based on a thiophene oligomer active layer exposed to 1-butanol vapours.
Dielectric properties of barium strontium titanate / non ferroelectric oxide ceramic composites
2001
International audience; Barium strontium titanate ceramics present high dielectric permittivity and tunability. In order to reduce their permettivity and loss tangent while keeping tunability, various composites of barium strontium titanate oxide...
Electric polarization of Onsager fluids
2002
The problem of correct determination of electrical and optical characteristics of molecules of dielectric fluids can actually be brought to problem of description of the effective internal field which consist of the field included by external sources and the cumulate electric field of molecules on the medium including intermolecular interactions. An attempt was made to modify the model Onsager theory. A polarizable molecular dipole enclosed in spherical cavity is substituted for a rigid one submerged in polarizable medium which fills the cavity. The local dielectric permittivity of the Heaviside type is replaced for the oscillating, rapidly damping function of Fresnel integral. The analytic…
Tuning the dielectric properties of hafnium silicate films
2007
The influence of Si concentration in hafnium silicate dielectrics on thermal stability and dielectric permittivity was analyzed. A phase diagram was developed using GIXRD and FTIR measurement. The stabilization of the ''higher-k'' cubic/tetragonal phase for annealing temperatures up to 1000^oC with a steady increase in capacitance was demonstrated for Hf"0"."9"4Si"0"."0"6O"2 films. It was also shown that the stabilization of nano-crystalline Hf"0"."8"0Si"0"."2"0O"2 films can be realized for annealing temperatures up to 900^oC. The influence of TiN electrodes on the dielectric constant and the leakage current characteristic was also investigated. A permittivity increase for annealing tempera…