Gallium contents-dependent improved behavior of sol–gel-grown Al:Ga co-doped ZnO nanostructures

This paper evaluates the improved structural, physical and optical characteristics of aluminum (Al) and gallium (Ga) co-doped ZnO (AGZO) thin film nanostuructures (NSs) synthesized on p-type Si(100) substrate via sol–gel-assisted spin-coating methods. Effects of varying Ga contents (1–5 at.%) on the structure, morphology and photoluminescence (PL) of AGZO films (fixed Al doping of 1 at.%) were determined. Samples were annealed at 500 °C for 3 h and characterized using XRD, FESEM, PL measurements. As-grown NS films revealed hexagonal wurtzite structure with average grain size ranged between 27 and 55 nm. Increase in Ga contents was found to not only reduce the grain size but altered the shape of NSs from nanoparticles (NPs) to nanorods to nanoleaves to nanopeanuts-like morphology. PL spectra displayed a strong UV peak and a broadband in the range of 381–388 nm, attributed to the defect and oxygen vacancy recombination mechanism. The estimated optical band gap of AGZO NSs (3.26–3.20 eV) was lower than pure ZnO films (3.37 eV).