K. Lmimouni

An Organic Nanoparticle Transistor Behaving as a Biological Spiking Synapse

Molecule-based devices are envisioned to complement silicon devices by providing new functions or by implementing existing functions at a simpler process level and lower cost, by virtue of their self-organization capabilities. Moreover, they are not bound to von Neuman architecture and this feature may open the way to other architectural paradigms. Neuromorphic electronics is one of them. Here, a device made of molecules and nanoparticles-a nanoparticle organic memory field-effect transistor (NOMFET)—that exhibits the main behavior of a biological spiking synapse is demonstrated. Facilitating and depressing synaptic behaviors can be reproduced by the NOMFET and can be programmed. The synaptic plasticity for real-time computing is evidenced and described by a simple model. These results open the way to rate-coding utilization of the NOMFET in dynamical neuromorphic computing circuits.

Traps and Interface Fixed Charge Effects on a Solution-Processed n-Type Polymeric-Based Organic Field-Effect Transistor

Organic field-effect transistors based on poly{[N,N0-bis(2-octyldodecyl)- naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,50-(2,20-bithiophene)}, [P(NDI2OD-T2)n], were fabricated and characterized. The effect of octadecyltrichlorosilane (OTS) a self-assembled monolayer (SAM) grafted on to a SiO2 gate dielectric was investigated. A significant improvement of the charge mobility (μ), up to 0.22xa0cm2/Vxa0s, was reached thanks to the OTS treatment. Modifying some technological parameters relating to fabrication, such as solvents, was also studied. We have analyzed the electrical properties of these thin-film transistors by using a two-dimensional drift–diffusion simulator, Integrated System Engineering-Technology Computer Aided Design (ISE-TCAD®). We studied the fixed surface charges at the organic semiconductor/oxide interface and the bulk traps effect. The dependence of the threshold voltage on the density and energy level of the trap states has also been considered. We finally found a good agreement between the output and transfer characteristics for experimental and simulated data.

A comparative TCAD simulations of a P-and N-type organic field effect transistors: field-dependent mobility, bulk and interface traps models

Pentacene and Polyera™ N2200 based-organic field effect transistors (OFETs), have been fabricated and simulated in a bottom-gate/back contacts configuration. The simulations were processed with the help of 2D drift–diffusion model. Comparison and analysis of the electrical characteristics of both n- and p-channel OFETs have been investigated. The study was centred on the electrical performance of every structure in term of mobility, fixed charge at the oxide/semiconductor interface and bulk traps density and its related energy. The dependence of the transfer characteristic on the grain boundaries traps state, in the case of pentacene, has been also outlined. Comparison between the simulation results and our experimental data show a good agreement. We finally present how our model can be applied to different devices with different channel length and we analyse their relationship with extracted electrical parameters.