Influence of Mn doping on the microstructure and optical property of ZnO

Abstract

Undoped and Mn doped ZnO samples with different percentage of Mn content (1 mol%, 2 mol% and 3mol%) were synthesized by a simple solvo-thermal method. We have studied the structural, chemical and optical properties of the samples by using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray (EDX) analysis, Fourier transform infrared (FTIR) spectroscopy and UV-VIS spectroscopy. The XRD spectra show that all the samples are hexagonal wurtzite structures. The lattice parameters calculated for the Mn doped ZnO from the XRD pattern were found to be slightly larger than those of the undoped ZnO, which indicates substitution of Mn in ZnO lattice. SEM photograph shows the grain size of undoped ZnO is bigger than the Mn doped ZnO's indicating hindrance of grain growth upon Mn doping. As the Mn doping increases the optical band gap decreases for the range of Mn doping reported here.

Bright Red Luminescence and Structural Properties of Eu<sup>3+</sup> Ion Doped ZnO by Solution Combustion Technique

“…Using the atomic weight concept, the Equation (1) was translated to grams/mol and used to obtain 3 gr of ZnO powder for all the 0, 1, 3, 5, 7, and 10 wt% Eu 3+ ion concentrations with respect to 3 gr of ZnO. From the translated grams/mol Equation (1) (no shown), 8.31 gr of Zn(NO 3) ) 2 •6H 2 O, 3.68 gr of H 2 NCONH 2 plus the numerous of grams corresponding to each Eu 3+ ion concentration were mixing with 20 ml of H 2 O and stirring vigourosly in a flask glas and after put on a hot plate at 500˚C, after a few minutes the reactive solution boils, foams, ignites, and burns with a incandescent flame at a approximate temperature of 1200˚C [26] producing 3 gr of ZnO powders approximately. After all the samples are annealing at 900˚C by 20 h. The ZnO:Eu 3+ samples thus obtained were structurally characterized by X-ray diffraction (XRD) technique using a Philips PW 1800 diffractometer with Cu kα radiation (1.5406 Å), XPS method was used to verify the Zn-O, Eu-O and O1s bonding energies (BE), the photoluminescence (PL) of the ZnO:Eu 3+ samples was studied by means of a spectrofluorometer FluoroMax-P that uses a xenon lamp as excitation source, The wavelength excitation was of 270 nm, and finally, the morphology of the ZnO:Eu 3+ powders was recorded using a scanning electron microscopy SEM) JEOL JSM 840 A.…”

“…In the last few decades, the semiconductor zinc oxide (ZnO) with a wide band gap energy (3.37 eV) at room temperature and high exciton binding energy (60 meV) [1], has been used as host material for the doping of rare-eart (RE) and transition metals (TM) ions, which exhibit optical and magnetic activity [2]- [6]. The REdoped ZnO nanocrystals have an high potential to be used in integrated optoelectronic devices such as infrared and visible (blue, green, red) luminescent devices because they present a highly efficient luminescence even at room temperature [7]- [11]; the emission process is determined by the internal dynamics of the RE 3+ electronics transitions governed by the relative energy of the 4f emitting level including the direct 4f-4f and indirect process 5 D 0 → 7 f i with i = 0 -4.…”

Influence of Mn doping on ZnO defect-related emission

“…Such an effect is usually observed in ZnO:Mn samples at a low Mn content (< 2 mol.%) and has been attributed to bandgap decrease caused by exchange interaction between d electrons of Mn and s and p electrons of the host bands [7,12].…”

“…The reported data on ZnO:Mn materials show that doping ZnO with Mn results in appearance of absorption in the visible spectral region, which exhibits itself as an unstructured "tail" in the absorption spectra [12,[17][18][19][20][21][22]. The intensity of this tail arises, and its spectral boundary shifts toward lower energies with increasing the Mn content [12,17,19,21,22], which produces at first yellow, then orange and at last reddish-brown color of the samples [2,19,22].…”

“…The intensity of this tail arises, and its spectral boundary shifts toward lower energies with increasing the Mn content [12,17,19,21,22], which produces at first yellow, then orange and at last reddish-brown color of the samples [2,19,22]. This effect was attributed to absorption of incident photons by Mn Zn 2+ ions caused by intra d-shell electron transitions from the ground to excited states [17,19].…”