Multifractal properties of Pyrex and silicon surfaces blasted with sharp particles

The blasting of brittle materials with sharp particles is an important fabrication technology in many industrial processes. In particular, for microsystems, it allows the production of devices with feature sizes down to few tens of microns. An important parameter of this process is the surface roughness of post-blasted surfaces. In this work the scaling properties of Pyrex glass and silicon surfaces after bombardment with alumina particles are investigated. The targets were bombarded at normal incidence using alumina particles with two different average sizes, 29 µm and 9 µm. This investigation indicates that the resulting surfaces are multifractal. Applying multifractal detrended fluctuation analysis (MFDFA) allowed us to determine the singularity spectrum of the surfaces. This spectrum did not depend on the target material or on the size of the particles. Several parameters quantifying relevant quantities were determined. It was found that long range correlations are responsible for the observed multifractal behaviour

U-shaped bilayer graphene channel transistor with very high Ion/Ioff ratio

A novel graphene transistor architecture is reported. The transistor has a U-shaped geometry and was fabricated using a gallium focused ion beam (FIB). The channel conductance was tuned with a back gate. The Ion/Ioff ratio exceeded 10E5

Microembossing of ultrafine grained Al: microstructural analysis and finite element modelling

Ultra fine grained (UFG) Al-1050 processed by equal channel angular pressing (ECAP) and UFG Al-Mg-Cu-Mn processed by high pressure torsion (HPT) were embossed at both room temperature and 300 °C, with the aim of producing micro-channels. The behaviour of Al alloys during the embossing process was analysed using finite element (FE) modelling. The cold embossing of both Al alloys is characterised by a partial pattern transfer, a large embossing force, channels with oblique sidewalls and a large failure rate of the mould. The hot embossing is characterised by straight channel sidewalls, fully transferred patterns and reduced loads which decrease the failure rate of the mould. Hot embossing of UFG Al-Mg-Cu-Mn produced by HPT shows a potential of fabrication of microelectromechanical system (MEMS) components with micro channels