Guided growth of in-plane lateral SiNWs led by indium catalysts
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1178-AA07-07
Guided growth of in-plane lateral SiNWs led by indium catalysts Linwei Yu, Oumkelthoum Moustapha, Maher Oudwan and Pere Roca i Cabarrocas Laboratoire de Physique des Interfaces et des Couches Minces (LPICM), Ecole Polytechnique, CNRS, 91128 Palaiseau, France
ABSTRACT Here we report a new in-plane solid-liquid-solid (IPSLS) mode for obtaining in-plane silicon nanowires (SiNW), which can be controlled and directly guided into various desired patterns for circuit architecture. Indium catalyst drops are firstly formed by a H2 plasma reduction of a thin layer of ITO on Corning glass substrate and then covered by an a-Si:H layer deposited at low temperature (100 oC-200 oC). The growth of SiNWs is activated in a reacting-gas-free thermal annealing process and led by the indium catalyst drops, that absorb and transform the a-Si:H matrix into crystalline SiNWs behind. At least two guided modes, that is, the a-Si:H channel guided mode and the step edge guided mode, can be applied to effectively control the growth routes for the lateral SiNWs. This guided growth of the IPSLS SiNWs lays an important basis for realizing various SiNWs-based device applications directly on top of low-cost substrates.
INTRODUCTION Silicon nanowires (SiNWs), obtained via the well-known vapor-liquid-solid (VLS) growth mechanism [1], provide important basis for exploiting various novel nano-electronic device prototypes, like the SiNW-based single electron transistor [2] and bio-sensors [3], where the SiNWs serve as both the functional elements and the electrical interconnections. Compared to the 0-dimension (0D) dots and 2D well structures, the 1D nanostructures offer an extra spatial freedom to grow directly into more complicated and potentially more functional networks or circuits. To fulfill this promise, a critical requirement is to be able to control effectively the growth paths of the SiNWs, not just into the simple straight ones, but directly into a continuous and non-overlapping network of SiNWs with a desired layout for specific functionality. Even though effective control over the size, morphology and position of SiNWs produced in VLS mode have been successfully demonstrated, a guided growth of SiNWs directly into predesigned patterns seems to go beyond the capability of the VLS mechanism. This is due to the fact that, in the VLS growth mode, once the SiNW growth is initiated, no (or very limited) control can be effectively imposed on the movement of the catalyst drops (which are immersed in a gas phase environment during growth)[4-6], and therefore the produced SiNWs are basically vertical and straight, or with bending or kinking morphologies arising from inner structural defects [7]. Recently, template methods have been proposed to force the catalyst drops into nanoscaled channels and to achieve a guided growth of the SiNWs in VLS mode, for example, by using the pore arrays in Al2O3 membranes [8]. However, putting aside the fact that the fabrication of the template by itself is an extra step, the effective location and feed
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