Article

# Ballistic FET modeling using QDAME: quantum device analysis by modal evaluation

T. J. Watson Res. Center, IBM Corp., Yorktown Heights, NY, USA

IEEE Transactions on Nanotechnology (Impact Factor: 1.8). 01/2003; DOI: 10.1109/TNANO.2002.807388 Source: IEEE Xplore

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**ABSTRACT:**In this paper, a novel device structure (Si1 − xGex/Si/Si1 − xGex hetero-structure), which is named as “center-channel (CC) double-gate (DG) MOSFET,” is proposed. Device performance of the proposed FET structure was investigated with our two-dimensional quantum-mechanical simulator which produces a self-consistent solution of Poisson–Schrödinger equations and the current continuity equation. The CC operation of CC-NMOS is confirmed from the electron density distribution and the band lineups as well as the lowest energy wave function. Current–voltage characteristics including the trans-conductance (Gm) of CC-MOSFET are carefully compared with those of the conventional DG-NMOS to evaluate the distinct feature of the proposed FET structure. Our simulation revealed that the proposed FET demonstrates the enhanced (about (∼1.6 × ) current drive and 60% Gm. Finally, the short-channel effects of CC and DG MOSFET, both of which demonstrate excellent sub-threshold behaviors and open the possibility of device scaling down to sub-20 nm.Molecular Simulation 01/2005; 31(12):825-830. · 1.06 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**The goal of this work is theoretical analyses of two prospective nanoelectronic devices. The first of them, the metal-oxide-semiconductor field-effect transistor (MOSFET) is the cornerstone of present day integrated circuit technology. We explore the ultimate size scaling limits of MOSFETs as their critical feature dimensions are scaled down below 10 nm. At that size, the physics of electron transport in these devices radically changes from quasi-equilibrium drift-diffusion to ballistic propagation. A proper description of such a regime requires a quantitative account of two-dimensional electrostatics and quantum mechanical effects such as direct source-to-drain tunneling. We have carried out extensive numerical simulations of nanoscale transistors, including these effects, using a self-consistent solution of the Poisson and Schrodinger equations. The results show that advanced silicon transistors can provide voltage gain at gate lengths as small as 4 nm. However, the device sensitivity to unavoidable variations of the dimensions during fabrication, and power consumption grow exponentially in this regime. The second device under study, the superconductor balanced comparator, is based on the quantum mechanical quantization of flux through superconducting loops. This device is a key component of Rapid Single-Flux-Quantum (RSFQ) circuits which can be used for digital signal processing at sub-THz frequencies, with extremely small power consumption, albeit at deep refrigeration. Alternatively, the comparator may be used for measurement of current (or magnetic flux) with sub-picosecond time resolution. We show that the signal detection sensitivity of the balanced comparator, with realistic parameters, may be limited only by the fundamental quantum fluctuations.01/2008; - [Show abstract] [Hide abstract]

**ABSTRACT:**We describe the two-dimensional simulation of a bent resonant tunneling diode structure which displays vortices in its total current density pattern over a range of applied bias. In contrast, a double gate n-MOSFET is shown where such circulation exists in individual subband states but does not survive in the total current density solution. Both devices are simulated assuming ballistic quantum transport in Si at 300 K.Journal of Computational Electronics 12/2003; 2. · 1.01 Impact Factor

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