Abstract
Silicon nanowires (NWs) and vertical nanowire-based Si/Ge heterostructures are expected to be building blocks for future devices, e.g. field-effect transistors or thermoelectric elements. In principle two approaches can be applied to synthesise these NWs: the 'bottom-up' and the 'top-down' approach. The most common method for the former is the vapour-liquid-solid (VLS) mechanism which can also be applied to grow NWs by molecular beam epitaxy (MBE). Although MBE allows a precise growth control under highly reproducible conditions, the general nature of the growth process via a eutectic droplet prevents the synthesis of heterostructures with sharp interfaces and high Ge concentrations. We compare the VLS NW growth with two different top-down methods: The first is a combination of colloidal lithography and metal-assisted wet chemical etching, which is an inexpensive and fast method and results in large arrays of homogenous Si NWs with adjustable diameters down to 50 nm. The second top-down method combines the growth of Si/Ge superlattices by MBE with electron beam lithography and reactive ion etching. Again, large and homogeneous arrays of NWs were created, this time with a diameter of 40 nm and the Si/Ge superlattice inside.
Original language | English |
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Pages (from-to) | 2555-2561 |
Number of pages | 7 |
Journal | Thin Solid Films |
Volume | 518 |
Issue number | 9 |
DOIs | |
Publication status | Published - 26 Feb 2010 |
Externally published | Yes |
Keywords
- Electron beam lithography
- Molecular beam epitaxy
- Reactive ion etching
- Si/Ge heterostructures
- Silicon nanowires
- Wet chemical etching