In this paper the formation of antimony (Sb) nanowires (NWs) by a focused Ga ion beam approach and their gas sensing capability is reported. The NWs with uniform diameters of only 25 nm and lengths up to several microns are synthesized at predefined positions at room temperature in an ion beam induced self-assembling process. Then individual Sb-NWs are deposited on insulating substrates and provided with gold electrodes. Subsequently sensing characteristics of individual Sb-NWs are investigated at room temperature for H2O, CO, H2, He, O2 and ethanol over a wide concentration range. The Sb-NWs exhibit selective sensing properties for ethanol and H2O with exceptional sensitivities of more than 17 000 and 60 000, respectively.

We demonstrate the formation of a complementary metal-oxide semiconductor compatible micro scale pH sensor with an antimony (Sb) nanowire network as the solid state pH electrode. The sensor is formed combining well known semiconductor processing techniques with a focused ion beam based approach inducing the self assembled formation of Sb nanowires in room temperature ambient without using any additional material source. The microscale pH sensor shows a highly linear relation in standardized pH buffer solutions with a sensitivity of 55.9 mV/pH and a very short response time of less than 8 s.

Sb nanowires with a homogeneous distribution of diameters of about 25 nm and length up to several microns are synthesized by a FIB induced self-assembling process. In contrast to a broad class of techniques for nanowire growth, neither heating of the sample nor any additional materials source is required, thereby being compatible with on-chip microelectronics. We propose a synthesis model similar to the well known vapor-liquid-solid mechanism with Ga acting as catalyst. The vapour-liquid-solid mechanism deals with the fact that a catalytic metal particle on the sample surface forms a liquid alloy cluster if the ambient temperature is high enough and serves as the preferential site for adsorption of reactant. It is supposed that supersaturation is the driving force for nucleation of seeds at the interface between the alloy cluster and the substrate surface giving rise to a highly anisotropic growth of nanostructures. We assume that FIB processing produces mobile Ga species on the surface which rapidly agglomerate forming catalytic nanoclusters. Sputtered Sb diffuses on the surface and acts as a quasi-vapor phase source. When the solved Sb concentration exceeds saturation, nucleation sites will be formed which initiate the precipitation of the Sb. We integrated such synthesized NWs in CMOS compatible resitivity type gas sensors.

The impact of high energy Ga ion beams focused to diameters below 100nm on antimony (Sb) substrates offers a new approach for the formation of pure Sb nanowires. In contrast to several well-known processes for bottom–up fabrication of one-dimensional nanostructures, for this process neither additional temperature treatment nor any additional material component is needed. Initially, the resulting nanostructures are completely amorphous and show very homogeneous diameters in the range of 20nm. Lengths up to several microns can be achieved. Annealing at temperatures around 150°C leads to re-crystallization of these nanowires.

The impact of high energy Ga ion beams focused to diameters below 100nm on substrates such as Ge and Sb offers a new approach for the formation of nanowires. In contrast to several well‐known processes for bottom‐up fabrication of one‐dimensional nanostructures, for this process neither additional temperature treatment nor any additional material component is needed. The resulting nanostructures are completely amorphous and show very homogeneous diameters in the range of 15 to 30nm. Lengths up to several microns can be achieved.

Ion beams focused to diameters in the range of several tens of nanometers offer an interesting opportunity for maskless processing in the nanoscale regime. Under certain sputter conditions a periodic height modulation in the form of ripples and dots on a submicron length scale develops during broad beam ion exposure as observed for semiconductor materials [1] – [4], metals [5], [6], insulator surfaces [7], and semimetals (e.g., graphite [8]). To gain full use of FIB techniques a fundamental understanding of the interaction of ion beams with the substrate material is required.

We present a focused ion beam-based approach for the synthesis of an antimony nanofiber network. The nanofibers, with a homogeneous distribution of diameters of about 25 nm and lengths up to several microns, are synthesized in a self-assembling process without any additional material source at room temperature. It is possible to recrystallize the as-grown amorphous nanofibers by moderate rapid thermal annealing at 473 K. These results have been verified by means of scanning electron microscopy, Auger electron spectroscopy, high-resolution transmission electron microscopy, selected area electron diffraction, and energy dispersive x-ray analysis. As this approach is not limited solely to the material discussed here, other substrates (e.g., GaSb and Ge) and ion sources should extend this method to other materials, which offers a great potential for future nanoscale devices and applications.

In this work, we present an experimental study of the morphological and chemical evolution of the (100) GaSb surface after 50keV focused Ga+ ion beam exposure using scanning electron microscopy, X-ray diffraction, Auger electron spectroscopy and room temperature raman measurements. A honeycomb-like structure consisting of many cells evolved under the GaSb surface implanted with 50keV Ga+ ions for ion fluences of 2.5×1015ions/cm2. The cell diameter and the thickness of the walls partitioning the cells were about 60 and 20nm respectively. During further FIB implantation the subsurface cavities expanded in the surface direction and form a microtexture of filaments about 25nm in diameter. Above a Ga fluence of 6.25×1016ions/cm2 the onset of nanofibers growth was observed taking place in close proximity to the FIB modified surface. The nanofibers are amorphous with remarkably uniform diameters in the range of about 25nm incorporating GaSb nanocrystallites with cubic zinc blende structure. A growth model is proposed based on the idea of a catalytic vapour liquid solid nanowire growth mechanism.

GaAs, GaSb and antimony substrates were exposed to the focused ion beam at varying ion fluences. Depending on process parameters, nanostructures such as Ga dots on GaAs and nanofibers on GaSb and Sb substrates were formed. To end up in ordered arrays of these nanostructures, pre-patterning of the substrates was done.