Sol-gel derived Al and Ga co-doped ZnO nanoparticles: Structural, morphological and optical investigation

Abstract

A sequence of Aluminum and Gallium co-doped ZnO nanoparticles (AGZ NPs) were synthesized by sol-gel method. The structural and morphological characteristics were explored by the advanced means of X-ray diffractometer (XRD) and transmission electron microscope (TEM), and the optical and photoluminescence properties were evaluated via UV–visible spectrophotometer and photoluminescence (PL), respectively. The AGZ NPs formed during the thermal treatment process exhibit well hexagonal wurtzite structure and slight (101) preferred orientation growth, the average sizes calculated from XRD are in the ranges from 23.9 to 32.4 nm which is corroborated well with TEM. The spherical and rod-shaped morphology of the resulted samples are authenticated by TEM analysis. UV–vis absorption spectra results indicate the introduction of Ga3+ is beneficial to the optical absorption property and the utilization efficiency of visible light. The optical energy band gap shows the initial decrease under low Ga concentration which increases further with increasing of Ga concentration. The exported PL spectra shows four fluorescence emission peaks attributed to the different intrinsic properties and defects therein. Simultaneously, AGZ2 suggests a minimum recombination rate of e−/h+ pairs while the temperate Al/Ga co-doping proportion gives rise to finer crystallite dimension, lower optical energy band gap and lower recombination rate of e−/h+ pairs.