A nanostructure is a structure, especially a semiconductor device, which has dimensions of only a few nanometers. The III-V semiconductors are materials that are obtained by combining group III. A elements with group V. A elements (e.g. GaP, GaAs,…).
Our department research is also the growth of GaP (gallium phosphide) nanostructures (nanowires, nanocones) for different applications. The nanostructures are grown by MOVPE (Metal Organic Vapour Phase Epitaxy) technique. The fields of application of nanostructures are wide from optical and chemical to biological applications.
GaP nanowires have the potential for application as antireflection coating for solar cells (Fig. 1). The Role of antireflection coating is to avoid the reflection of phonons from the surface and allow their absorption into the solar cells. The main benefit of using nanowires as antireflective coating is their broadband and omnidirectional character. However, nanowires are fragile and they can break under tiny mechanical stresses. A way to avoid this problem is to fill gaps between individual NWs with another material, e.g. thin nanostructural layer as ZnO (zinc oxide). The other benefit of using ZnO is the widening of the spectral sensitivity range of solar cells to the UV region.
SEM images: GaP nanowires (left), GaP nanowires covered with ZnO layer (right).
GaP nanocones covered with Ag nanoparticles (Fig. 2) are a very promising material for surface-enhanced Raman spectroscopy (SERS = Surface-enhanced Raman spectroscopy). SERS is a selective and highly sensitive method for the identification of chemical species in a wide variety of fields, including materials science, biosensing, and electrochemistry. The main advantage of SERS is the detection of chemicals at very low concentrations (in the range from 10-2 to 10-20 M).
SEM image of GaP nanocones covered with Ag nanoparticles.
Publications:
Novák, J., Laurenčíková, A., Eliáš, P., Hasenöhrl, S., Sojková, M., Dobročka, E., Kováč, J.jr., Kováč, J., Ďurišová, J., and Pudiš, D.: Nanorods and nanocones for advanced sensor applications, Applied Surface Sci 461 (2018) 61-65.
Lettrichová, I., Laurenčíková, A., Pudiš, D., Novák, J., Goraus, M., Kováč, J.jr., Gaso, P., and Nevrela, J.: 2D periodic structures patterned on 3D surfaces by interference lithography for SERS, Applied Surface Sci 461 (2018) 171-174.
Laurenčíková, A., Eliáš, P., Hasenöhrl, S., Kováč, J.jr., Szobolovszký, R., and Novák, J.: GaP nanocones covered with silver nanoparticles for surface-enhanced Raman spectroscopy, Applied Surface Sci 461 (2018) 149-153.
Kúdela, R., Šoltýs, J., Kučera, M., Stoklas, R., Gucmann, F., Blaho, J., Mičušík, M., Pohorelec, O., Gregor, M., Brytavskyi, I.V., Dobročka, E., and Gregušová, D.: Technology and application of in-situ AlOx layers on III-V semiconductors, Applied Surface Sci 461 (2018) 33-38.
Laurenčíková, A., Novotný, I., Hasenöhrl, S., Dérer, J., Eliáš, P., Kováč, J., Kováč, J., Dobročka, E., Novák, J., : Formation of a compact Ga-doped ZnO layer over vertical free-standing GaP nanowires. Applied Surface Sci 395 (2017) 162-165.
Stoklas, R., Gregušová, D., Blaho, M., Fröhlich, K., Novák, J., Matys, M., Yatabe, Z., Kordoš, P., Hashizume, T., : Influence of oxygen-plasma treatment on AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors with HfO2 by atomic layer deposition: leakage current and density of states reduction,. Semicond. Sci Technol. 32 (2017) 045018.
Novák, J., Laurenčíková, A., Hasenöhrl, S., Eliáš, P., Kováč, J., : Methanol sensor for integration with GaP nanowire photocathode. Proc. SPIE 10248, Nanotechnology VIII (2017) 102480E.
Novák, J., Laurenčíková, A., Hasenöhrl, S., Eliáš, P., Novotný, I., Kováč, J., Valentin, M., Kováč, J., Ďurišová, J., Pudiš, D., : Optical and mechanical properties of a compact ZnO layer with embedded GaP nanowires. Applied Surface Sci 395 (2017) 180-184.
Gucmann, F., Kúdela, R., Rosová, A., Dobročka, E., Micusik, M., Gregušová, D., : Optimization of UV-assisted wet oxidation of GaAs,. J. Vacuum Sci Technol. B 35 (2017) 01A116. (VEGA 2/0105/13). (APVV 15-0243). (CENTE II).
Gregušová, D., Gucmann, F., Kúdela, R., Mičušík, M., Stoklas, R., Válik, L., Greguš, J., Blaho, M., Kordoš, P., : Properties of InGaAs/GaAs metal-oxide-semiconductor heterostructure field-effect transistors modified by surface treatment,. Applied Surface Sci 395 (2017) 140-144. (VEGA 2/0105/13). (CENTE). (APVV 14-0297).
Mikulics, M., Arango, Y., Winden, A., Adam, R., Hardtdegen, A., Grützmacher, D., Plinski, E., Gregušová, D.,Novák, J., Kordoš, P., Moonshiram, A., Marso, M., Sofer, Z., Lüth, H., Hardtdegen, H., : Direct electro-optical pumping for hybrid CdSe nanocrystal/III-nitride based nano-light-emitting diodes. Applied Phys. Lett. 108 (2016) 061107.
Gucmann, F., Kúdela, R., Kordoš, P., Dobročka, E., Gaži, Š., Dérer, J., Liday, J., Vogrinčič, P., Gregušová, D., : III-As heterostructure field-effect transistors with recessed ex-situ gate oxide by O2 plasma-oxidized GaAs cap. J. Vacuum Sci Technol. B 33 (2015) 01A111. (VEGA 2/0105/13). (VEGA 2/0098/13). (CENTE).
Laurenčíková, A., Eliáš, P., Hasenöhrl, S., Kováč, J., Mikolášek, M., Vávra, I., Novák, J., : Analysis of the core–shell interface between zinc-blende GaP and wurtzite ZnO. Solid-State Electr. 100 (2014) 7-10.
Eliáš, P., Hasenöhrl, S., Laurenčíková, A., Rosová, A., Novák, J., : Annealing of gold nanoparticles on GaP(111)B: initial stage of GaP nanowire growth. Phys. Status Solidi RRL 8 (2014) 321-324.
Novák, J., Šutta, P., Vávra, I., Eliáš, P., Hasenöhrl, S., Laurenčíková, A., Novotný, I., : Columnar microstructure of the ZnO shell layer deposited on the GaP nanowires. Applied Surface Sci 312 (2014) 162-166.