Site-controlled formation of single Si nanocrystals in a buried SiO₂ matrix using ion beam mixing

Abstract

For future nanoelectronic devices – such as room-temperature single electron transistors – the site-controlled formation of single Si nanocrystals (NCs) is a crucial prerequisite. Here, we report an approach to fabricate single Si NCs via medium-energy Si+ or Ne+ ion beam mixing of Si into a buried SiO2 layer followed by thermally activated phase separation. Binary collision approximation and kinetic Monte Carlo methods are conducted to gain atomistic insight into the influence of relevant experimental parameters on the Si NC formation process. Energy-filtered transmission electron microscopy is performed to obtain quantitative values on the Si NC size and distribution in dependence of the layer stack geometry, ion fluence and thermal budget. Employing a focused Ne+ beam from a helium ion microscope, we demonstrate site-controlled self-assembly of single Si NCs. Line irradiation with a fluence of 3000 Ne+/nm2 and a line width of 4 nm leads to the formation of a chain of Si NCs, and a single NC with 2.2 nm diameter is subsequently isolated and visualized in a few nanometer thin lamella prepared by a focused ion beam (FIB). The Si NC is centered between the SiO2 layers and perpendicular to the incident Ne+ beam.

An atomic force microscope integrated with a helium ion microscope for correlative nanoscale characterization

“…Correlative AFM and HIM imaging is demonstrated in Fig. 2 by imaging silicon nanopillars [ 30 ]. The HIM offers a large field of view, which allows for the cantilever to be navigated onto the region of interest ( Fig.…”

A Compact Model Based on Bardeen’s Transfer Hamiltonian Formalism for Silicon Single Electron Transistors

“…QD diameters d dot of around 3 nm are chosen in order to permit room-temperature operation of the SET which requires a QD size smaller than 10 nm [30]. Furthermore, the fabrication of self-aligned silicon QDs in a silicon dioxide layer has been demonstrated experimentally with ion-beam mixing and subsequent annealing for QD sizes of about 3 nm [31]. For obtaining measurably large currents, the distance t ed should not exceed 2 nm while dot formation by ion-beam mixing requires a minimum distance of at least 0.5 nm.…”

Structural and optical characteristics determined by the sputtering deposition conditions of oxide thin films

“…They are intensely investigated due to their versatile properties, such as high transmission in the visible range [12,13] and broad energy bandgap [14][15][16], among others. Among the important applications of these oxides are materials with dielectric properties used in the fabrication of metasurface structures, transparent conductive oxides and buffer layers used in solar cells, and materials used in sensor technology [6,8,[17][18][19][20][21]. Materials with dielectric properties (e.g., SiO 2 and ZnO) exhibit a dependence of the electrical resistance with temperature [22,23].…”