Surface modification by high-energy heavy-ion irradiation in various crystalline ZnO facets

0546410 - ÚJF 2022 RIV GB eng J - Journal Article
Jagerová, Adéla - Mikšová, Romana - Romanenko, Oleksandr V. - Sofer, Z. - Slepička, P. - Mistřík, J. - Macková, Anna
Surface modification by high-energy heavy-ion irradiation in various crystalline ZnO facets.
Physical Chemistry Chemical Physics. Roč. 23, č. 39 (2021), s. 22673-22684. ISSN 1463-9076. E-ISSN 1463-9084
Research Infrastructure: CANAM II - 90056
Institutional support: RVO:61389005
Keywords : ZnO surface * irradiation * AFM
OECD category: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect)
Impact factor: 3.945, year: 2021
Method of publishing: Limited access
https://doi.org/10.1039/D1CP02388H

Self-assembled surface nanoscale structures on various ZnO facets are excellent templates for the deposition of semiconductor quantum dots and manipulation with surface optical transparency. In this work, we have modified the surface of c-, m- and a-plane ZnO single-crystals by high-energy W-ion irradiation with an energy of 27 MeV to observe the aspects of surface morphology on the optical properties. We kept ion fluences in the range from 5 x 10(9) cm(-2) to 5 x 10(11) cm(-2) using the mode of single-ion implantation and the overlapping impact mode to see the effect of various regimes on surface modification. Rutherford backscattering spectroscopy in the channeling mode (RBS-C) and Raman spectroscopy have identified a slightly growing Zn-sublattice disorder in the irradiated samples with a more significant enhancement for the highest irradiation fluence. Simultaneously, the strong suppression of the main Raman modes and the propagation of the modes corresponding to polar Zn-O vibrations indicate disorder mainly in the O-sublattice in non-polar facets. The surface morphology, analysed by atomic force microscopy (AFM), shows significant changes after ion irradiation. The c- and a-plane ZnO exhibit the formation of small grains on the surface. The m-plane ZnO forms a sponge-like surface for lower fluences and grains for the highest fluence. The surface roughness itself increases with the irradiation fluence as shown by AFM measurement as well as spectroscopic ellipsometry (SE) analysis. The damage caused by high-energy irradiation leads to non-radiative processes and suppression of the near-band-edge peak as well as the deep-level emission peak in the photoluminescence spectra. Furthermore, the refraction index n and the extinction coefficient k of irradiated samples, determined by SE, have features corresponding to the particular exciton states blurred and are slightly lower in the optical bandgap region especially for the polar c-plane ZnO facet.
Permanent Link: http://hdl.handle.net/11104/0323177