The nitrogen doping of ZnO film deposited by the magnetron sputtering method is subsequently realized by the hydrothermal synthesis method.The nitrogen-doped ZnO film is preferably(002) oriented.With the increase of hexamethylenetetramine(HMT) solution concentration,the average grain size of the film along the 002 direction almost immediately decreases and then monotonously increases,conversely,the lattice strain first increases and then decreases.The structural evolution of the film surface from compact and even to sparse and rough is attributed to the enhanced nitrogen doping content in the hydrothermal process.The transmission and photoluminescence properties of the film are closely related to grain size,lattice strain,and nitrogen-related defect arising from the enhanced nitrogen doping content with HMT concentration increasing.
A series of 103-oriented aluminum-doped zinc oxide(AZO) films were deposited on glass substrates via directcurrent pulse magnetron reactive sputtering at different O2-to-Ar gas flow ratios(GFRs). The optical properties of the films were characterized using the fitted optical constants in the general oscillator model(which contains two Psemi-Tri oscillators) through the use of measured ellipsometric parameters. The refractive index dispersion data below the interband absorption edge were analyzed using a single-oscillator model. The fitted optical energy gap obtained using the singleoscillator model clearly shows a blue shift, followed by a red shift, as the GFR increases from 0.9/18 to 2.1/18. This shift can be attributed to the change in the free electron concentration of the film, which is closely related to the film stress.In addition, the fitted β value indicates that the AZO film falls under the ionic class. The photoluminescence spectrum indicates a photoluminescence mechanism of the direct and wide energy gap semiconductor.
White light-emitting YVO_4:1 mol.%Dy^(3+),x mol.%Eu^(3+) phosphor powders with order morphology and well crystallization were hydrothermally synthesized at 180°C. The microstructure, white-light emission, and light-emitting mechanism of the powders were carefully studied using X-ray diffractometry, scanning electron microscopy and photoluminescence spectra. The excitation and emission spectra of the phosphor powders indicated the coexistence of efficient energy transfer from Eu^(3+) to Dy^(3+) and inefficient energy transfer from Dy^(3+) to Eu^(3+) besides the energy transfer from VO_4^(3–) to Eu^(3+). Increasing the Eu~(^(3+)) concentration initially enhanced and then weakened the luminescent intensity of Dy^(3+). The white-light emissions of YVO_4:1 mol.%Dy^(3+),x mol.%Eu^(3+) phosphor powders were both related to the energy transfer between VO_4^(3–) and Dy^(3+)/Eu^(3+), as well as between Eu^(3+) and Dy^(3+). The inefficient energy transfer from Dy^(3+) to Eu^(3+) was first found.
