Fabrication of silicon nanowires by ion beam irradiation
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Fabrication of silicon nanowires by ion beam irradiation
J. Song1, Z. Y. Dang1, S. Azimi1, M. B. H. Breese1,2,*
1
Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 2
Singapore Synchrotron Light Source (SSLS), 5 Research Link, National University of Singapore, 5 Research Link, Singapore 117603
ABSTRACT Silicon nanowires are becoming more important because of increasing requirements of the small scale and dense integration of devices. We report a top-down fabrication method for silicon nanowires using high-energy ion beam irradiation of bulk p-type silicon followed by electrochemical etching. Silicon nanowires with a diameter of ~50nm have been fabricated and densely patterned nanowire arrays fabricated in different resistivity silicon wafers. With a suitable support structure, free standing silicon nanowires are also achieved. We investigate results depending on silicon wafer resistivity and location within the irradiated area.
*
Corresponding author: Song Jiao: [email protected]
INTRODUCTION Silicon nanowires attract much research interest due to their promising applications and potential in many fields. With feature sizes shrinking to nanometer scales, silicon nanowires have a large surface-to-volume ratio and can be used as chemical or biological sensors with high sensitivity and low power consumption [1, 2]. Silicon nanowires also possess special thermoelectric properties compared to its bulk counterpart [3] and are used in thermoelectric devices [4]. Silicon waveguides with size of a few hundred nanometers are single mode with low loss and attractive for optical communication purpose [5]. Silicon nanowires may also be used in lithium ion batteries [6] and solar cells [7] to increase the efficiency of these devices. The electronic, optical and transport properties of silicon nanowires have been deeply investigated [810]. Wagner et al. reported fabrication of silicon nanowires using vapor-liquid-solid (VLS) technique in 1964 [11]. This method is good for mass production, is commonly used and has been improved by many groups [12, 13]. Some groups also try to fabricate silicon nanowires by a relatively rapid method such as chemical etching [14] or electrochemical etching [6]. These methods are good for large-area fabrication and applications, but may often encounter post fabrication manipulation which is usually not precise enough to make single wire devices. Other methods using nanoimprinting [15] or silicon plasma etching [16] usually use silicon-oninsulator (SOI) wafers which are costly and the structures are limited to two dimensions. In this paper, we report a fabrication method combining nanolithography, ion beam irradiation and electrochemical etching, which can achieve single silicon nanowire with size and position are predetermined and has the potential for three dimensional structures. The basic method using high energy ion irradiation on p-type silicon wafer followed by electrochemical etching in hydrofluoric acid solution has bee
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