Distinct defect appearance in Gd implanted polar and nonpolar ZnO surfaces in connection to ion channeling effect

0519076 - ÚJF 2020 RIV US eng J - Journal Article
Jagerová, Adéla - Malinský, Petr - Mikšová, Romana - Nekvindová, P. - Cajzl, J. - Akhmadaliev, S. - Holý, V. - Macková, Anna
Distinct defect appearance in Gd implanted polar and nonpolar ZnO surfaces in connection to ion channeling effect.
Journal of Vacuum Science & Technology A : Vacuum, Surfaces and Films. Roč. 37, č. 6 (2019), č. článku 061406. ISSN 0734-2101. E-ISSN 1520-8559
R&D Projects: GA MŠMT EF16_013/0001812; GA ČR GA18-03346S; GA MŠMT LM2015056
Institutional support: RVO:61389005
Keywords : Rutherford back-scattering spectrometry in channeling mode * X-ray diffraction * scattering
OECD category: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect)
Impact factor: 2.166, year: 2019
Method of publishing: Limited access
https://doi.org/10.1116/1.5125320

We present results of (0001) c-plane, (11-20) a-plane, and m-plane (10-10) ZnO bulk crystals which were implanted with 400-keV Gd+ ions using fluences of 5 x 10(14), 1 x 10(15), 2.5 x 10(15), and 5 x 10(15) cm(-2). Structural changes during the implantation and subsequent annealing were characterized by Rutherford back-scattering spectrometry in channeling mode (RBS-C). The angular dependence of the backscattered ions (angular scans) in c-, a-, and m-plane ZnO was realized to get insight into structural modification and dopant position in various crystallographic orientations. X-ray diffraction (XRD) with mapping in reciprocal space was also used for introduced defect identification. Defect-accumulation depth profiles exhibited differences for c-, a-, and m-plane ZnO, with the a-plane showing significantly lower accumulated disorder in the deeper layer in Zn-sublattice, accompanied by the preservation of ion channeling phenomena in a-plane ZnO. Enlargement of the main lattice parameter was evidenced, after the implantation, in all orientations. The highest was evidenced in a-plane ZnO. The local compressive deformation was seen with XRD analysis in polar (c-plane) ZnO, and the tensile deformation was observed in nonpolar ZnO (a-plane and m-plane orientations) being in agreement with RBS-C results. Raman spectroscopy showed distinct structural modification in various ZnO orientations simultaneously with identification of the disordered structure in O-sublattice. Nonpolar ZnO showed a significant increase in disorder in O-sublattice exhibited by E-2(high) disappearance and enhancement of A(1)(LO) and E-1(LO) phonons connected partially to oxygen vibrational modes. The lowering of the E-2(low) phonon mode and shift to the lower wavenumbers was observed in c-plane ZnO connected to Zn-sublattice disordering. Such observations are in agreement with He ion channeling, showing channeling effect preservation with only slight Gd dopant position modification in a-plane ZnO and the more progressive diminishing of channels with subsequent Gd movement to random position with the growing ion fluence and after the annealing in c-plane and m-plane ZnO.
Permanent Link: http://hdl.handle.net/11104/0304098