Structural, FTIR, optical and photoluminescence investigation of Zn_1-xRE_xO nanoparticles for optical and power operation devices

Structural, morphological, FTIR, optical and photoluminescence (PL) measurements of Zn_1-xRE_xO nanoparticles with RE = Y, La and x (0.00 ≤ x ≤ 0.20) are reported. The wurtzite structure is confirmed for all samples and the lattice parameters, Zn–O bond length, porosity, crystallite size, lattice strain and residual stress are increased by increasing x to 0.20, but they are higher for La samples than Y. The grain sizes are 180, 330, and 460 nm for the pure, Y and La samples. The addition of RE to ZnO generally shifts FTIR absorption peaks, Debye temperature, and elastic modulus to higher values, but the shift is higher for La samples than Y. Although excitonic energy is constant for all samples, the energy gap E_g was increased by increasing x to 0.20, but it is higher for La samples than Y. Furthermore, the dielectric lattice constant, density of charge carriers, and electrical conductivity are increased by increasing x to 0.10, followed by a decrease to 0.20. The opposite behavior is true for dielectric loss and optical conductivity. The PL intensity shows four continuous visible peaks of near UV, blue, green, and red. Interestingly, the intensity of blue emission is greater than that of near UV, such that [(I_blue/I_UV)] > 1]. Furthermore, for x > 0.10 samples, there is another lowest intensity IR emission peak centred at 824 nm (1.507 eV). These results are well explained and strongly recommend the RE doped samples for the applications of optoelectronic and high-power operating devices. To our knowledge, the present investigation probably has never been reported elsewhere.