Odd electron diffraction patterns (EDPs) have been obtained by transmission electron microscopy (TEM) on silicon nanowires grownviathe vapour–liquid–solid method and on silicon thin films deposited by electron beam evaporation. Many explanations have been given in the past, without consensus among the scientific community: size artifacts, twinning artifacts or, more widely accepted, the existence of new hexagonal Si phases. In order to resolve this issue, the microstructures of Si nanowires and Si thin films have been characterized by TEM, high-resolution transmission electron microscopy (HRTEM) and high-resolution scanning transmission electron microscopy. Despite the differences in the geometries and elaboration processes, the EDPs of the materials show great similarities. The different hypotheses reported in the literature have been investigated. It was found that the positions of the diffraction spots in the EDPs could be reproduced by simulating a hexagonal structure withc/a= 12(2/3)^1/2, but the intensities in many EDPs remained unexplained. Finally, it was established that all the experimental data,i.e.EDPs and HRTEM images, agree with a classical cubic silicon structure containing two microstructural defects: (i) overlapping Σ3 microtwins which induce extra spots by double diffraction, and (ii) nanotwins which induce extra spots as a result of streaking effects. It is concluded that there is no hexagonal phase in the Si nanowires and the Si thin films presented in this work.

Stress-induced leakage current (SILC) is studied in 10 nm HfO₂ metal-insulator-metal capacitors. Three regimes are observed in the current-time characteristics, namely, (1) an absorption current, (2) a quasi linear increase of current with time (SILC), and (3) thermal breakdown. Magnitude of SILC is strongly correlated to the nature of the cathode (being large for TiN and weak for Pt and Au), showing that SILC is governed by electron injection. Recovery is observed when short-circuiting the samples, pointing out that SILC is a reversible phenomenon. Desorption current and SILC are not correlated, which indicates that different defects control the absorption current and SILC. SILC is ascribed to the generation of oxygen vacancies upon hot electron injection, while recovery is ascribed to the recombination of oxygen ions with vacancies. In the SILC regime, the current varies as Ktⁿ (n = 1.15 at room temperature). Bias and temperature dependence of K and n are studied. The dependence of K on bias can be described either by a Fowler-Nordheim law or by an exponential law, while the exponent n is almost independent of bias. When temperature is increased, K increases according to an Arrhenius law and n decreases. SILC is modeled by considering the generation of oxygen vacancies by hot electron impact and subsequent electron trapping at vacancies (hopping conduction). An analytical expression for SILC growth is obtained from first order kinetics.

In this paper, we demonstrate a top-down fabrication technique for nanometre scale silicon carbide (SiC) pillars using inductively coupled plasma etching. A set of experiments in SF₆-based plasma was carried out in order to realize high aspect ratio SiC nanopillars. The etched SiC nanopillars using a small circular mask pattern (115 nm diameter) show high aspect ratio (7.4) with a height of 2.2 µm at an optimum bias voltage (300 V) and pressure (6 mTorr). Under the optimal etching conditions using a large circular mask pattern with 370 nm diameter, the obtained SiC nanopillars exhibit high anisotropy features (6.4) with a large etch depth (>7 µm). The etch characteristic of the SiC nanopillars under these conditions shows a high etch rate (550 nm min⁻¹) and a high selectivity (over 60 for Ni). We also studied the etch profile of the SiC nanopillars and mask evolution over the etching time. As the mask pattern size shrinks in nanoscale, vertical and lateral mask erosion plays a crucial role in the etch profile of the SiC nanopillars. Long etching process makes the pillars appear with a hexagonal shape, coming from the crystallographic structure of α-SiC. It is found that the feature of pillars depends not only on the etching process parameters, but also on the crystallographic structure of the SiC phase.