FABRICATION AND EXPERIMENTAL STUDY OF METAL NANOANTENNAS FOR PHOTOABSORPTION INCREASING IN ACTIVE LAYER OF THIN- FILM SOLAR BATTERY
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The article is dedicated to fabrication and diagnostics development methods of the metallic nanoantennas for thin-film solar batteries application. Fabrication results of the experimental samples consisting of single nanoantennas and two-dimensional arrays of antennas by focused ion-beam milling are presented. The optimal regimes of metal deposition on the semiconductor substrate are selected, which gives the possibility for thin silver films deposition (50-70 nm thick) with low relative surface roughness and grain sizes less than 20 nm. The optimal doses of ion beam irradiation are found for gold and silver films of 50 nm thickeness which lead to correspondence between the dimensions of actual fabricated nanoantenna and its design model with accuracy less than 10 nm. The fabricated nanoantenna clusters are investigated by scanning electron microscopy and atomic force microscopy in semi-contact mode. The unique techniques of scanning near-field optical microscopy are developed using these samples. These techniques give the possibility for direct measurement of local electromagnetic fields at optical frequencies with resolution less than 100 nm. The developed technological regimes of low-roughness thin - film deposition, focused ion beam milling and the methods of fabrication parameters control of the nanoantennas will be used upon fabrication of nanoantenna coatings of this particular design for effectiveness growth of the thin - film solar batteries. The developed fabrication and diagnostics methods make it possible to create other golden and silver structures with high arbitrary resolution (less than 20 nm) for various plasmonics and nanophotonics applications.