In3+ doped ZnGa2O4 nanoparticles: Difference in the luminescence properties upon optical and electrical excitations

Abstract

In the present study, influence of In3+ doping on the structural and luminescence properties of ZnGa2O4 nanoparticles has been investigated in detail. In3+ doped ZnGa2O4 nanoparticles with size less than 10 nm have been prepared at a relatively low temperature of 120 °C. From X-ray diffraction (XRD) and photoluminescence (PL) studies, different Ga3+ structural units, with varying number of In3+ as next nearest neighbors (NNN) around Ga3+ in GaO6 octahedra, have been identified and their relative extent is evaluated by assuming a binomial distribution of Ga3+ and In3+ cations in the lattice. The GaO6 octahedra are found to be unaffected by In3+ doping as confirmed by the identical values of oxygen positional parameter “x” derived from Rietveld refinement of the XRD patterns. Alternating current powder electroluminescence (ACPEL) has been demonstrated for the first time from the nanoparticles of undoped and In3+ doped ZnGa2O4. Due to the formation of GaO6 structural units with varying number of In3+ as next near neighbors around Ga3+, tuning of emission wavelength is observed from the nanoparticles upon UV excitation. However, under an applied electric field during electroluminescence (EL) measurements, only regular GaO6 structural units undergo excitation and Ga-O-In linkages mainly act as scattering centers leading to less favorable electrical excitation of corresponding GaO6 structural units. The findings have potential relevance in the area of wide band gap semiconductor technology employing doped ZnGa2O4 nanoparticles.