Morphology, structure and emission of Al-doped ZnO nanocrystal films
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The morphology, structure and emission of Al-doped ZnO nanocrystals (NCs) with the different Al contents (1–4 at.%) were studied by means of the scanning electronic microscopy, energy dispersive X ray spectroscopy, X-ray diffraction and photoluminescence (PL) methods. Ultrasonic spray pyrolysis was applied to obtain the ZnO:Al films. To stimulate the crystallization, the ZnO:Al films were annealed at 400 °C for 4 h in a constant nitrogen flow (8 L/min). It is shown that the Al incorporation in the ZnO films with the concentrations of 2–4 at.% stimulates: the reduction of ZnO:Al grain sizes, decreasing the film crystallinity owing to disordering the ZnO:Al crystal lattice, the change of the surface morphology and increasing the surface roughness. Meanwhile, Al-doping the ZnO films at the concentrations ≤ 2 at.% enlarge significantly the PL intensity of the near band edge emission. Last fact testifies to quality improving the ZnO:Al films. Simultaneously, the PL intensities of green and orange PL bands, connected with the native defects: VZn and Oi, fall down. The ZnO NC films with Al-doping ≤ 2 at.% still keep the planar surface morphology that is important for their applications in electronic device structures.
The authors thank the Secretary of Investigation and Postgraduate Study at National Polytechnic Institute (Projects 20180495, 20170821, 20170633 and 20170667) and National Council of Science and Technology (CONACYT) of Mexico (Project 258224) for the financial support.
- 27.C.H. Ahn, S.K. Mohanta, N.E. Lee, H.K. Cho, Appl. Phys. Lett. 94, 271904 (2009)Google Scholar