13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Growth of Grass Like Architectures on Si Substrate and Its Mechanism Study Lijiao Hu, Yang Ju*, Hosoi Atsushi Department of Mechanical Science and Engineering, Nagoya University, Nagoya 464-8603, Japan * Corresponding author: ju@mech.nagoya-u.ac.jp Abstract Grass like architectures were synthesized directly on Silicon substrate by thermal oxidation method with nickel catalyst at low temperature. Humidity and catalyst played an important role in the fabrication of the grass like architectures. The morphology of the grass-like architectures was controlled by heating temperature. The grass like architectures were observed by scanning electron microscope (SEM, JSM-7000FK), Energy-dispersive X-ray (EDX) and X-ray diffraction (XRD). The grass like architectures were approximately 8-70μm in size with 1-2.5μm width leaves. The growth of grass like architectures affected by oxidation, vertical stress induced, and horizontal compressive stress was studied in details. Keywords Grass like architectures, Thermal oxidation, Nickel catalyst, Compressive stress 1. Introduction Cuprous oxide (Cu2O) is a p-type semiconductor metal oxide with a direct band gap of about 2.17 eV. Due to its unique optical, electrical, and magnetic properties[1–3], and other properties such as simplicity and low cost of preparation, nontoxic nature, and abundance, it has attracted great attention and been widely applied in solar energy conversion[4], photocatalysis[5], sensors[6], negative electrode materials for lithium-ion batteries[7], electrochromism[8], and antibacterials[9]. The fundamental properties of micro/nanostructure semiconductors are found to be dependent on their architectures, including geometry, morphology, and hierarchical structures[10]. Therefore, great efforts have been devoted to artificially control the morphology of Cu2O micro/nanocrystals in the past several years[11]. Different Cu2O nano architectures have been synthesized, such as nanowhiskers[12], nanowires[13], nanocubes[14], nanorods[15], nanospheres[16], nanoflowers[17], nanocages[18]. A variety of methods have been reported to synthesize nanoflowers of different materials. These methods include hydrothermal synthesis[19], sol–gel method[20], chemical vapor deposition[21], ultrasonic pyrolysis[22], electrodeposition method[23], and solution routes[24]. Herein, we have developed novel syntheses of grass like Cu2O architectures on silicon substrate with nickel-based catalyst at a low temperature. Although many studies proposed the evolution of different structures, the ability to manifest the precise growth mechanism of Cu2O micro/nanostructures is still quite limited. In this work, the growth mechanism of Cu2O grass-like architecture on silicon substrate was studied through the phenomenon of several contrast experiments. 2. Experiment Commercial silicon wafer with a thickness of 0.50 mm was cut into square samples which were 20mm×20mm in size. The substrates were then ultrasonically (BRANSONIC1510) cleaned with acetone, washed with ethanol and de-ionized water sequentially to dissolve the contaminations. Nickel based catalyst used in this experiment was the high temperature electrically conductive coating material (Pyro-DuctTM 598-C, AREMCO, INC.). Catalyst was manually daubed on the silicon substrate as the shape of islands with diameter around 2-3 mm. Cu powder was dispersed around Ni on the substrate. Grass like architectures were then synthesized by heating the sample in wet air atmosphere at 200°C temperature for 3h.
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