Abstract-In this paper, using three-dimensional statistical numerical simulations, the authors study the intrinsic parameter fluctuations introduced by random discrete dopants, line edge roughness (LER), and oxide-thickness variations in realistic bulk MOSFETs scaled to 25, 18, 13, and 9 nm. The scaling is based on a 35 nm MOSFET developed by Toshiba, which has also been used for the calibration of the authors' "atomistic" device simulator. Special attention is paid to the accurate resolution of the individual discrete dopants in the drift-diffusion simulations by introducing density-gradient quantum corrections for both electrons and holes. In the LER simulations, two scenarios have been adopted: In the first one, LER follows the prescriptions of the International Roadmap for Semiconductors; in the second one, LER is kept constant close to the current best values. Combined effects of the different sources of intrinsic parameter fluctuations have also been simulated in the 35 nm reference devices and the results for the standard deviation of the threshold voltage compared to the measured values.

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Abstract-The Z 2 -FET operation as capacitor-less DRAM is analyzed using advanced 2D TCAD simulations for IoT applications. The simulated architecture is built based on actual 28 nm FD-SOI devices. It is found that the triggering mechanism is dominated by the front-gate bias and the carrier's diffusion length. As in other FB-DRAMs, the memory window is defined by the ON voltage shift with the stored body charge. However, the Z 2 -FET's memory state is not exclusively defined by the inner charge but also by the reading conditions.

The band-modulation and sharp-switching mechanisms in Z 2 -FET device operated as a capacitorless 1T-DRAM memory are reviewed. The main parameters that govern the memory performance are discussed based on detailed experiments and simulations. This 1T-DRAM memory does not suffer from super-coupling effect and can be integrated in sub-10 nm thick SOI films. It offers low leakage current, high current margin, long retention, low operating voltage especially for programming, and high speed. The Z 2 -FET is suitable for embedded memory applications.

The aim of this paper is to present a flexible and open-source multi-scale simulation software which has been developed by the Device Modelling Group at the University of Glasgow to study the charge transport in contemporary ultra-scaled Nano-CMOS devices. The name of this new simulation environment is Nano-electronic Simulation Software (NESS). Overall NESS is designed to be flexible, easy to use and extendable. Its main two modules are the structure generator and the numerical solvers module. The structure generator creates the geometry of the devices, defines the materials in each region of the simulation domain and includes eventually sources of statistical variability. The charge transport models and corresponding equations are implemented within the numerical solvers module and solved self-consistently with Poisson equation. Currently, NESS contains a drift–diffusion, Kubo–Greenwood, and non-equilibrium Green’s function (NEGF) solvers. The NEGF solver is the most important transport solver in the current version of NESS. Therefore, this paper is primarily focused on the description of the NEGF methodology and theory. It also provides comparison with the rest of the transport solvers implemented in NESS. The NEGF module in NESS can solve transport problems in the ballistic limit or including electron–phonon scattering. It also contains the Flietner model to compute the band-to-band tunneling current in heterostructures with a direct band gap. Both the structure generator and solvers are linked in NESS to supporting modules such as effective mass extractor and materials database. Simulation results are outputted in text or vtk format in order to be easily visualized and analyzed using 2D and 3D plots. The ultimate goal is for NESS to become open-source, flexible and easy to use TCAD simulation environment which can be used by researchers in both academia and industry and will facilitate collaborative software development.