P-09 Ion implantation of Gd, Er and Au into various crystallographic cuts of ZnO single crystals – structural vs. photoluminescence properties

Topic: Photonic and optical properties of solids

P. Nekvindová^1*, J. Cajzl¹, K. Jeníčková¹, A. Jagerová^2,3, A. Macková^2,3, J. Oswald⁴, U. Kentsch⁵

¹ Department of Inorganic Chemistry, University of Chemistry and Technology, Technická 5, 166 28 Prague, Czech Republic

² Nuclear Physics Institute, Czech Academy of Sciences, v. v. i., 250 68 Řež, Czech Republic

³ Department of Physics, J.E. Purkinje University, České mládeže 8, 400 96 Ústí nad Labem, Czech Republic

⁴ Institute of Physics, Czech Academy of Sciences, v.v.i., Cukrovarnická 10/112, 162 00 Prague, Czech Republic

⁵ Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden, Germany

^* E-mail: nekvindp@vscht.cz

 Keywords: ion implantation, Gd, Er, Au, ZnO, luminescence

Abstract: Ion implantation is an efficient tool for ZnO doping with various ions. Previous results  show the importance of ZnO surface crystallographic orientation towards the ion beam, which influence the process of recombination of Zn/O interstitial and vacancy positions. But recently the defect removal seem to be complicated and unknown. By varying the concentration and position of the oxygen vacancies as well as by changing the band gap structure luminescence of ZnO is significantly influenced. Therefore, luminescence spectroscopy is a suitable tool for monitoring mentioned changes.

In this contribution, the single-crystal ZnO wafers with (0001), (10‑10) and (11‑20) crystallographic planes were implanted by Gd⁺, Er⁺ and Au⁺ ions accelerated to 400 keV. The ion-implantation fluences used for the mentioned single-crystal ZnO were 5×10¹⁴ and 1×10¹⁵ ions/cm². The implanted samples were subsequently annealed in O₂ at 600 °C for 1 hour. The ion concentration-depth profiles as well as disorder-depth profiles caused by ion implantation and subsequent annealing were examined by Rutherford backscattering spectrometry (RBS) and RBS/channelling (RBS/C) measurements. Additionally, the Raman spectroscopy was performed to study the ZnO structure changes. The main attention of our work was focused on the investigation of luminescence properties. We focused particularly on the relationship between the two main intrinsic luminescence bands of ZnO at around 375 and 530 nm and studied in detail the possibility of controlling the luminescence properties of ZnO by varying the position of the short-wavelength bands. The results showed different structural damage reflected in shifts of wide defect-related luminescence band (DLE, i.e. deep level emission) of ZnO. The resulting luminescence properties of ZnO depended significantly on the choice of dopants and crystallographic cuts of ZnO as well as on the conditions of subsequent annealing. The practical results were also compared with theoretical simulations of various dopant positions in ZnO structure performed by density functional theory (DFT) simulations.

Acknowledgements

The research has been carried out at the CANAM (Centre of Accelerators and Nuclear Analytical Methods) infrastructure LM 2015056. This work was supported by the Czech Science Foundation (GACR No. 18-03346S).