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Carbon monoxide and ammonia are inorganic agents found both in nature and in the human body, which is of great interest for modern sensing. First, in concentrations of the order of 1 ppm agents are produced by human and can be markers of changes in human health. Second, at concentrations of the order of 100 ppm, carbon monoxide and ammonia are toxic and hazardous. This work is aimed at fabrication and study of precise, technological and relatively cheap sensors compatible with a gas and liquid medium for CO and NH3 detection, respectively.

In this paper, we study the effect of the height and diameter of vertically aligned silicon structures on their optical properties. Structures with different geometry were formed using nanosphere lithography and dry etching. Nanosphere lithography was realized with 0.9 and 2 μm latex spheres. The etching process was carried out through a formed mask (template) composed of 0.9 and 2 μm latex spheres, respectively. The diameter of the spheres and the etching time determined the size of the formed structures and their optical properties. A significant reduction of the total reflection with height as well as blue shift of the minimum with diameter decrease were observed.