X-Ray Luminescence of Zinc Oxide Thick Films

Effect of Plasma Treatment on the Luminescent and Scintillation Properties of Thick ZnO Films Fabricated by Sputtering of a Hot Ceramic Target

“…As was indicated in the Introduction, previously studied thick ZnO films obtained by the same method and not subjected to plasma treatment exhibited a very weak NBEL or its complete absence under X-ray excitation [41,42]. High-temperature annealing, although it improved the crystalline quality of the films, led to intensification of DL due to different rates of desorption of zinc and oxygen elements and did not allow the appearance of any significant NBEL signal [41,42].…”

“…To use a ZnO film as a scintillator, it is first necessary to achieve high intensity of the fast NBEL component under X-ray excitation and high transmittance, which is important when using a scintillator in transmission geometry. As was mentioned in the Introduction, thick ZnO films that were not exposed to plasma treatment do not show NBEL and, hence, are not of interest for us (see, e.g., [41,42] for such a study). In order to smooth the surface and increase transmission of the films, the plasma-treated samples were processed by a chemical-mechanical method.…”

“…Among the problems of using ZnO films for detecting ionizing radiation, one can note their poor emission characteristics compared, for example, with arrays of ZnO nano/microcrystals or doped ceramics [40]. A common disadvantage of ZnO films is the much stronger visible luminescence component as compared to the NBEL band-this is especially pronounced in relatively thick micron-scale films [41,42]. However, the major drawback is, in general, the low light output when irradiated with γand X-rays.…”

“…This method provides an extremely high growth rate of the films due to cluster emission and good adhesion to a sapphire substrate. However, due to the tendency of the deposit to amorphize, as well as nonstoichiometry, such films demonstrated either a complete absence of luminescence or a broad band of visible luminescence resulting from lattice defects [41,42]. Such emission has slow decay kinetics and is not of interest for scintillation applications.…”

X-ray Luminescent Properties of Zinc Oxide Films on the Sapphire M and A-Plane

“…The limiting factor for the mass use of ZnO films is their low growth rate. The method of " uncooled target" with a growth rate increased up to 16 nm/s used in [8,9] has not allowed producing the required result: the films were growing with defects, with prevailing green luminescence (GL) in their X-ray luminescence (XRL) spectra. Recrystallization annealing in the air at a temperature of 1000 • C for 10 h only resulted in a greater GL due to the generation of additional number of oxygen vacancies.…”