# Nanoelectronics

*The current status of mesoscopic physics thus seems somewhat like that of semiconductors physics in the 1940s when there was no reason to believe that vacuum tubes would ever be displaced. But…who knows?* **Supriyo Datta**

For over four decades, microelectronics industry has been characterized by an exponential growth of the performance of its products [1,2]. On one hand, the level of integration ("Moore's law") has increased, as well as the switching velocity and the functionality of integrated circuits. On the other hand, power consumption and cost per operation has decreased. Most of these developments have arisen as a direct consequence of the ability of the electronics industry to further reduce the size of conventional MOSFET. However, nowadays, there is a broad consensus that the geometric scaling of MOSFET is not enough to provide the expected performance of future electronic devices [1,2]. Thus, the scientific community has identified the "More Moore" domain as the strategy to evolve traditional CMOS devices by means of a trade-off between the geometrical scaling and the introduction of new technological solutions (high-κ dielectric, multiple gate transistors, stressed silicon, metal gates, etc.), known as "equivalent scaling" [1]. There is a wide agreement that these are currently the best strategies for the electronics industry in the 2007-2022 period predicted by the latest ITRS [1].

However, the scientific community is also searching for completely different alternatives to CMOS, since the long-term scaling required by Moore's law (4 nm channel length transistors predicted for 2022 [1]) will be technologically and economically unattainable. In this sense, the "Beyond CMOS" domain explores emerging electronic devices whose operation is based on different physical principles than MOSFET. For example, devices based on the control of spin orientation (“spintronics”), devices based on tunnel transport such as “resonant tunneling diodes” (RTD), devices based on “Coulomb Blockade” and ”Single-electron devices”. Materials different from bulk Silicon are also under investigation, such as “silicon nanowires” or "Carbon-based Nanoelectronics" (i.e. carbon nanotubes and graphene). It is currently not clear which of these proposals may replace the MOSFET. In any case, it is believed that in the near future some of these emerging devices can coexist with nanometer CMOS structures by using non-pure-electronic technologies (MEMS, sensors, etc), combined with new architectures (quantum computing, bio-inspired, etc.) or new connections (3D, "Silicon-on-Package") in what is known as the “More than Moore" domain [1,2].

### Noise in mesoscopic systems:

The problem of current fluctuations in mesoscopic systems touches on one of the deepest issues of physics: the wave-particle duality. Our objective is to simulate experimental current noise in different mesoscopic scenarios using the de Broglie-Bohm interpretation of quantum mechanics.

X.Oriols "Quantum mechanical effects on noise properties of nanoelectronic devices: Application to Monte Carlo simulation” IEEE Transaction on Electron Devices, vol.50 (9), 1830,(2003).

### High frequency effects in mesoscopic systems:

The study of quantum transport in time-dependent scenarios is a hard task either from an experimental (one does not want to see the parasitic capacitances) or a theorethcial point of view. We provide a wave packet approach to study the delicate quantum time-dependent tunneling phenomenology.

»A. Alarcón and **X.Oriols** “Computation of quantum electron transport with local current conservation using quantum trajectories,” Journal of Statistical Mechanics: Theory and Experiment 2009, P01051 (2009)

»**X.Oriols**, A.Alarcon and J.Mateos "Quantum transport under high-frequency conditions: application to bound state resonant tunneling transistors” Semicond. Sci. Technol. 19, L69-L73 (2004)

### Field effect transistors:

» G.Albareda, D.Jimenez and **X.Oriols** “Intrinsic noise in aggressively scaled field-effect transistors,”Journal of Statistical Mechanics: Theory and Experiment, 2009, P01044 (2009)

»**X.Oriols**, E.Fernàndez-Díaz, A.Alvarez and A.Alarcón “An Electron injection model for time-dependent simulators of nanoscale devices with electron confinement: Application to the comparison of the intrinsic noise of 3D-, 2D- and 1D- ballistic transistors” Solid State Electronics, vol. 51, 306 (2007) Special Issue on EUROSOI

»V.Sverdlov, **X. Oriols** and K.Likharev, "Effective Boundary Conditions for Carriers in Ultrathin SOI Channels" IEEE Transaction on Nanotechnology,vol.2 (1), 59, (2003).

### Resonant tunneling devices:

»**X. Oriols**, J. García, F. Martín, J. Suñé, T. González, J. Mateos, D. Pardo, O.Vanbesien "Towards the Monte Carlo simulation of resonant tunnelling diodes using time-dependent wavepackets and Bohm trajectories" Semicond. Sci. Technol., vol 14, 532 (2000).