Aluminium Induced Formation of Silicon Microrods from Nanosilicon via Gas Phase Transportation

The trend towards miniaturization of electrical engineering creates a need to study the properties of not only bulk silicon, but also nanoparticles based on it. Silicon nanoparticles and microrods have various interesting electrical properties, which can be used in the creation of microelectronic devices. The article describes the technique which leads to recrystallization of nanosilicon into extended microrods with silicon transfer via vapor upon annealing in the presence of aluminum precursors AlCl₃ or Al + AlCl₃. The morphology of and structure of microrods were studied by both optical and scanning electron microscopy, Raman spectroscopy, XRD, EDX methods. The microrods have a diameter of 0.5–2 μm, length up to 3000–5000 μm, are characterized by a cubic crystal structure, and have p-type conductivity. The current–voltage characteristics of the microrods have been studied, the heights of the metal–semiconductor barriers have been determined, and the temperature dependences of the conductivity have been obtained. The conductivity of the microrods increases significantly in air or in the presence of the oxidizing gas NO₂. The sensory response to NO₂ in the dark and under UV irradiation at room temperature has been studied. Photosensitivity is also observed: under IR laser irradiation, the conductivity increases by 2 orders of magnitude. To conclude, we present a convenient method for obtaining silicon microrods with interesting electrical and sensing properties which are promising for use in microelectronics.