On the impact of TiN film thickness variations on the effective work function of poly-Si/TiN/SiO/sub 2/ and poly-Si/TiN/HfSiON gate stacks

The impact of TiN film thickness variations on the effective work function (WF) of poly-Si/TiN/SiO/sub 2/ and poly-Si/TiN/HfSiON interfaces has been investigated. The electrical signatures of these gate stacks indicate that the concentration of Hf-Ti and Ti-Si bonds at the (poly-Si/TiN)/HfSiON and (poly-Si/TiN)/SiO/sub 2/ interface plays a significant role on the control of the gate stacks' WF. The density of these interfacial bonds and the related work function changes are correlated to the degree of nucleation of the TiN film on the dielectric.     

A new F(ast)-CMS NEGF algorithm for efficient 3D simulations of switching characteristics enhancement in constricted tunnel barrier silicon nanowire MuGFETs

In this paper, we present 3D quantum simulations based on Non-Equilibrium Green’s Function (NEGF) formalism using the Comsol Multiphysics^? software and on the implementation of a new Fast Coupled Mode-Space (FCMS) approach. The FCMS algorithm allows one to simulate transport in nanostructures presenting discontinuities, as the normal Coupled Mode-Space (CMS) algorithm does, but with the speed of a Fast Uncoupled-Mode Space (FUMS) algorithm (a faster algorithm that cannot handle discontinuities). We then use this new algorithm to explore the effect of local constrictions on the performance of nanowire MultiGate Field-Effect Transistors (MuGFETs). We show that cross-section variations in a nanowire result in the formation of energy barriers that can be used to improve the on/off current ratio and switching characteristics of transistors: (1) A small constriction resulting in a barrier of the order of a 0.1 eV can be used as an effective means to improve the subthreshold slope and minimize the on/off current ratio degradation resulting from SD tunneling in ultra scaled transistor, and (2) We also report a new variable barrier transistor (VBT) device concept that is able to achieve sub-kT/q subthreshold slope without using impact ionization or band-to-band tunneling. Intra-band tunneling through constriction barriers is used instead. The device is, therefore, fully symmetrical and can operate at very low supply voltages. A subthreshold slope as low as 56.5 mV/decade is reported at T=300 K. The VBT reported here breaks the 60 mV/dec barrier over more than five decades of subthreshold current, which is the widest current range reported so far.     

NBTI and hot-carrier effects in accumulation-mode Pi-gate pMOSFETs

Negative bias temperature instability (NBTI) and hot-carrier induced device degradation in accumulation-mode Pi-gate pMOSFETs have been studied for different fin widths ranging from 20 to 40 nm. The NBTI induced device degradation is more significant in narrow devices. This result can be explained by enhanced diffusion of hydrogen at the corners in multiple-gate devices. Due to larger impact ionization, hot-carrier induced device degradation is more significant in wider devices. Finally, hot-carrier induced device degradation rate is highest under stress conditions where V_GS = V_TH.     

Comparison of different surface orientation in narrow fin MuGFETs

Device performance characteristics are investigated for different surface orientation and doping concentration on accumulation-mode p-type and inversion-mode n-type MuGFETs. Short-channel effects and drain breakdown voltage are better is carrier transport is in the (1 0 0) direction than in the (1 1 0) direction. This is due to the larger Si/SiO₂ interface roughness, the higher density of interface state at (1 1 0) surfaces, and to the difference of effective mass. The mobility in PMOS devices, however, is much higher in the (1 1 0) direction than that in the (1 0 0) direction. For better performance of device, our results show that optimized fin orientation can improve device stability and performance.     

Industrial applications of ion track technology

It4ip sa is a spin out from the Université Catholique de Louvain (Belgium) dedicated to the development and production of unique templates and membranes based on the combination of ion track technology of polymers. It supplies customers with hi-tech products, state-of-the-art research and product development services with template capability to make high value added membranes.Notably based on results coming from several collaborative R&D projects supported by European and Regional funding, recent improvements of ion track technology open new doors for fast growing applications in niche markets. This paper reviews some of these Hi-Tec applications in different fields such as in healthcare (oncology, drug control release combined to implant and artificial organs etc.), energy (fuel cells and batteries etc.), water de-contamination and electronics (OLED etc.).     

Vertical (La,Sr)MnO3 Nanorods from Track‐Etched Polymers Directly Buffering Substrates

A novel and general methodology for preparing vertical, complex‐oxide nanostructures from a sol–gel‐based polymer‐precursor solutions is developed using track‐etched polymers directly buffering substrates. This method is able to develop a nanostructure over the entire substrate, the dimensions and localization of the vertical nanostructures being preset by the polymeric nanotemplate. Thereby, nanostructures with lateral sizes in the range of 100 to 300 nm and up to 500 nm in height have been grown. Two examples are presented herein, the latter being the evolution of the initial, metastable nanostructure. Specifically, La_0.7Sr_0.3MnO₃ polycrystalline rods are grown at mild temperatures (800 °C); upon strong thermal activation (1000 °C) they suffer a profound transformation into vertical, single‐crystalline (La,Sr)_xO_y nanopyramids sitting on a La_0.7Sr_0.3MnO₃ epitaxial wetting layer. The driving force for this outstanding nanostructural evolution is the minimization of the total energy of the system, which is reached by reducing the grain‐boundary, total‐surface, and strain‐relaxation energies. Finally, advanced electron‐microscopy techniques are used to highlight the complex phase separation and structural transformations occurring when the metastable state is overcome.     

Stable field emission from arrays of vertically aligned free-standing metallic nanowires

We present a fully elaborated process to grow arrays of metallic nanowires with controlled geometry and density, based on electrochemical filling of nanopores in track-etched templates. Nanowire growth is performed at room temperature, atmospheric pressure and is compatible with low cost fabrication and large surfaces. This technique offers an excellent control of the orientation, shape and nanowires density. It is applied to fabricate field emission arrays with a good control of the emission site density. We have prepared Co, Ni, Cu and Rh nanowires with a height of 3?μm, a diameter of 80?nm and a density of ～10(7)?cm(-2). The electron field emission measurements and total energy distributions show that the as-grown nanowires exhibit a complex behaviour, first with emission activation under high field, followed by unstable emission. A model taking into account the effect of an oxide layer covering the nanowire surface is developed to explain this particular field emission behaviour. Finally, we present an in situ cleaning procedure by ion bombardment that collectively removes this oxide layer, leading to a stable and reproducible emission behaviour. After treatment, the emission current density is ～1?mA?cm(-2) for a 30?V?μm(-1) applied electric field.     

Single-Crystalline Silicon Layer Transfer to a Flexible Substrate Using Wafer Bonding

This paper reports the successful transfer of a thin single-crystalline silicon film to a flexible, transparent polymer substrate. Thin-film silicon on polymer was realized by bonding a silicon-on-insulator (SOI) wafer to a flexible substrate using a spin-on polymer as an adhesive. The SOI wafer was thinned by a grinding operation followed by chemical mechanical polishing (CMP). The SOI was further thinned to the buried oxide using wet etchants. The residual stress in the transferred substrate was investigated by ultraviolet (UV) micro-Raman spectroscopy and numerical modeling. Both approaches showed that a low level of stress was created at the bonded interface during the layer transfer.