Functional Devices from Bottom-Up Silicon Nanowires: A Review.

This paper summarizes some of the essential aspects for the fabrication of functional devices from bottom-up silicon nanowires. In a first part, the different ways of exploiting nanowires in functional devices, from single nanowires to large assemblies of nanowires such as nanonets (two-dimensional arrays of randomly oriented nanowires), are briefly reviewed. Subsequently, the main properties of nanowires are discussed followed by those of nanonets that benefit from the large numbers of nanowires involved. After describing the main techniques used for the growth of nanowires, in the context of functional device fabrication, the different techniques used for nanowire manipulation are largely presented as they constitute one of the first fundamental steps that allows the nanowire positioning necessary to start the integration process. The advantages and disadvantages of each of these manipulation techniques are discussed. Then, the main families of nanowire-based transistors are presented; their most common integration routes and the electrical performance of the resulting devices are also presented and compared in order to highlight the relevance of these different geometries. Because they can be bottlenecks, the key technological elements necessary for the integration of silicon nanowires are detailed: the sintering technique, the importance of surface and interface engineering, and the key role of silicidation for good device performance. Finally the main application areas for these silicon nanowire devices are reviewed.

Improvement of AlN Film Quality Using Plasma Enhanced Atomic Layer Deposition with Substrate Biasing.

In recent years, plasma enhanced atomic layer deposition (PEALD) has emerged as a key method for the growth of conformal and homogeneous aluminum nitride (AlN) films at the nanoscale. In this work, the utilized PEALD reactor was equipped not only with a traditional remote Inductively Coupled Plasma source but also with an innovative additional power supply connected to the substrate holder. Thus, we investigate here the substrate biasing effect on AlN film quality deposited on (100) silicon. We report that by adjusting the ion energy via substrate biasing, the AlN film quality can be significantly improved. Indeed, compared to films commonly deposited without bias, AlN deposited with a platen power of 5 W displays a 14% increase in the number of N-Al bonds according to X-ray spectroscopy analysis. Moreover, after having integrated them into Metal-AlN-Si capacitors, the 5 W AlN film exhibits a permittivity increase from 4.5 to 7.0 along with a drastic drop of leakage current density of more than 5 orders of magnitude. The use of substrate biasing during PEALD is thereby a promising strategy for the improvement of AlN film quality.