Fine tuning of optical and dielectric characteristics of titanium dioxide (TiO 2), such as comple... more Fine tuning of optical and dielectric characteristics of titanium dioxide (TiO 2), such as complex refractive index, optical conductivity, and dielectric function, have been demonstrated by doping, and co-doping of antimony and bismuth for applications in terahertz (THz) spectral frequency range. The characterization has been performed using X-ray diffraction, THz time-domain spectroscopy, and Effective-Medium Approximation theory. The results show an increasing trend in the measured parameters with frequency and dopant concentration. Moreover, the conductivity of the samples in THz range fulfills the Drude Smith model.
ABSTRACT In this research article deep level green luminescence quenching, stability of ultraviol... more ABSTRACT In this research article deep level green luminescence quenching, stability of ultraviolet excitonic emission and structural properties of composite (ZnO)1−x (Cr2O3)x (x = 0, 5, 10 and 15 mol%) are investigated. X-ray diffraction has demonstrated polycrystalline wurtzite structured ZnO and established proper incorporation of Cr3+ at most likely on the Zn lattice sites. More likely, the crystallite size and lattice constants (c, a) decrease while consequently the dislocation density is increased. A pronounced excitonic UV emission due to band–band transition and a weak deep level green emission caused by the oxygen vacancies are observed at peak-wavelengths (358–370) nm and (536–538) nm respectively. The UV luminescence shows a blue-shift and well-built stability up-to 10 mol% Cr2O3; however for 15 mol% Cr2O3, both the UV and green emissions are completely suppressed while an orange emission appears at 640 nm. This emission is attributed to radiative recombination of a delocalized electron closed to the conduction band with deeply trapped hole in the oxygen interstitials (Oi- centers). Energy bandgap (Eg) is finely tuned from 3.35 eV to 3.46 eV. The exhibited blue shift in the energy bandgap is attributed to Burstein–Moss shift explained by the photon energy dependent measurements. The favorable assorted luminescence mechanisms are explained explicitly.
Fine tuning of optical and dielectric characteristics of titanium dioxide (TiO 2), such as comple... more Fine tuning of optical and dielectric characteristics of titanium dioxide (TiO 2), such as complex refractive index, optical conductivity, and dielectric function, have been demonstrated by doping, and co-doping of antimony and bismuth for applications in terahertz (THz) spectral frequency range. The characterization has been performed using X-ray diffraction, THz time-domain spectroscopy, and Effective-Medium Approximation theory. The results show an increasing trend in the measured parameters with frequency and dopant concentration. Moreover, the conductivity of the samples in THz range fulfills the Drude Smith model.
ABSTRACT In this research article deep level green luminescence quenching, stability of ultraviol... more ABSTRACT In this research article deep level green luminescence quenching, stability of ultraviolet excitonic emission and structural properties of composite (ZnO)1−x (Cr2O3)x (x = 0, 5, 10 and 15 mol%) are investigated. X-ray diffraction has demonstrated polycrystalline wurtzite structured ZnO and established proper incorporation of Cr3+ at most likely on the Zn lattice sites. More likely, the crystallite size and lattice constants (c, a) decrease while consequently the dislocation density is increased. A pronounced excitonic UV emission due to band–band transition and a weak deep level green emission caused by the oxygen vacancies are observed at peak-wavelengths (358–370) nm and (536–538) nm respectively. The UV luminescence shows a blue-shift and well-built stability up-to 10 mol% Cr2O3; however for 15 mol% Cr2O3, both the UV and green emissions are completely suppressed while an orange emission appears at 640 nm. This emission is attributed to radiative recombination of a delocalized electron closed to the conduction band with deeply trapped hole in the oxygen interstitials (Oi- centers). Energy bandgap (Eg) is finely tuned from 3.35 eV to 3.46 eV. The exhibited blue shift in the energy bandgap is attributed to Burstein–Moss shift explained by the photon energy dependent measurements. The favorable assorted luminescence mechanisms are explained explicitly.
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Papers by Amjid Iqbal