The role of band alignment in p-type conductivity of Na-doped ZnMgO: Polar versus non-polar

Zhang, H. H.; Pan, Xin; Li, Y.; Ye, Z. Z.; Lü, Bin; Chen, W.; Huang, Jun; Ding, Peng; Chen, S. S.; He, Haiping; Lu, J. G.; Chen, L. X.; Ye, C. L.

doi:10.1063/1.4869481

Cited by 19 publications

(7 citation statements)

References 22 publications

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“…In order to construct nonpolar ZnO-based light-emitting devices, the preparation of high-quality nonpolar p-type ZnO thin films is indispensable. Fortunately, it seems to be more promising to obtain nonpolar p-type ZnO thin films because the nonpolar films exhibit some advantages over polar films to obtain p-type behavior [9][10][11][12]. So far, there have been only a few studies dealing with p-type doping of nonpolar ZnO [13][14][15][16][17][18].…”

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confidence: 99%

Enhanced photoluminescence of nonpolar p-type ZnO film by surface plasmon resonance and electron transfer

Chen

Pan

et al. 2015

Opt. Lett.

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Nonpolar oriented Na-doped ZnO films were grown on m-plane sapphire substrates by plasma-assisted molecular beam epitaxy. The films show repeatable p-type conductivity with a hole concentration of about 3.0×10(16) cm(-3) as identified by the Hall-effect measurements. 10-fold enhancement in the near-band-edge (NBE) emission of the nonpolar p-type ZnO by employing Pt nanoparticle surface plasmons has been observed. In addition, the deep level emission has been entirely suppressed. The underlying mechanism behind the enhancement of NBE emission and the quenching of defect emission is a combination of the electron transfer and the resonant coupling between NBE emission and Pt nanoparticle surface plasmons.

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confidence: 99%

Enhanced photoluminescence of nonpolar p-type ZnO film by surface plasmon resonance and electron transfer

Chen

Pan

et al. 2015

Opt. Lett.

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“…The exploration of non-polar ZnO based films and quantum structure growth to avoid the polarization effects are ongoing [ 15 ]. On the other hand it was also proven that the polarity of the oxide films affects the doping efficiency of ZnO [ 16 ]. Therefore, the fundamental studies on acceptor doping in Zn 1−x Mg x O thin films are crucial towards the fabrication of ZnO based devices.…”

Section: Introductionmentioning

confidence: 99%

Polar and Non-Polar Zn1−xMgxO:Sb Grown by MBE

et al. 2022

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The article presents a systematic study of Sb-doped Zn1-xMgxO layers, with various concentrations of Mg, that were successfully grown by plasma-assisted MBE on polar a- and c- oriented and non-polar r-oriented sapphire substrates. X-ray diffraction confirmed the polar c-orientation of alloys grown on c-and a-oriented sapphire and non-polar structures grown on r-oriented substrates. A uniform depth distribution of the Sb dopant at level of 2 × 1020 cm−3 was determined by SIMS measurements. Raman spectroscopy revealed the presence of Sb-related modes in all samples. It also showed that Mg alloying reduces the compressive strain associated with Sb doping in ZnO. XPS analysis indicates that the chemical state of Sb atoms in ZnMgO is 3+, suggesting a substitutional position of SbZn, probably associated with two VZn vacancies. Luminescence and transmission spectra were measured to determine the band gaps of the Zn1-xMgxO layers. The band gap energies extracted from the transmittance measurements differ slightly for the a, c, and r substrate orientations, and the differences increase with increasing Mg content, despite identical growth conditions. The differences between the energy gaps, determined from transmission and PL peaks, are closely correlated with the Stokes shift and increase with the Mg content in the analyzed series of ZnMgO layers.

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“…In this context, semiconductor photocatalysis technology has attracted substantial interest as an effective approach for the degradation of different hazardous compounds present in polluted waters [1,2]. Among the various semiconductor photocatalysts, ZnO has drawn widespread interest owing to its exceptional features, as its wide optical band gap at room temperature (3.3 eV), large exciton binding energy (60 meV) and low cost coupled with its non-toxicity and availability [3][4][5][6][7]. Moreover, ZnO has proved its high potential to be exploited in a wide range of technological applications such as sensing [8], optoelectronic devices [9,10], transparent electronics [11] and in particular, as a photocatalyst to completely eliminate a variety of hazardous organic molecules under UV/solar irradiation [12].…”

Section: Introductionmentioning

confidence: 99%

In-Depth Structural and Optical Analysis of Ce-modified ZnO Nanopowders with Enhanced Photocatalytic Activity Prepared by Microwave-Assisted Hydrothermal Method

et al. 2020

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Pure and Ce-modified ZnO nanosheet-like polycrystalline samples were successfully synthesized by a simple and fast microwave-based process and tested as photocatalytic materials in environmental remediation processes. In an attempt to clarify the actual relationships between functionality and atomic scale structure, an in-depth characterization study of these materials using a battery of complementary techniques was performed. X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), energy-dispersive X-Ray spectroscopy-scanning transmission electron microscopy (STEM-XEDS), photoluminescence spectroscopy (PL) and UV–Visible absorption spectroscopy were used to evaluate the effect of Ce ions on the structural, morphological, optical and photocatalytic properties of the prepared ZnO nanostructures. The XRD results showed that the obtained photocatalysts were composed of hexagonal, wurtzite type crystallites in the 34–44 nm size range. The SEM and TEM showed nanosheet-shaped crystallites, a significant fraction of them in contact with bundles of randomly oriented and much smaller nanoparticles of a mixed cerium–zinc phase with a composition close to Ce0.68Zn0.32Ox. Importantly, in clear contrast to the prevailing proposals regarding this type of materials, the STEM-XEDS characterization of the photocatalyst samples revealed that Ce did not incorporate into the ZnO crystal lattice as a dopant but that a heterojunction formed between the ZnO nanosheets and the Ce–Zn mixed oxide phase nanoparticles instead. These two relevant compositional features could in fact be established thanks to the particular morphology obtained by the use of the microwave-assisted hydrothermal synthesis. The optical study revealed that in the ZnO:Ce samples optical band gap was found to decrease to 3.17 eV in the samples with the highest Ce content. It was also found that the ZnO:Ce (2 at.%) sample exhibited the highest photocatalytic activity for the degradation of methylene blue (MB), when compared to both the pure ZnO and commercial TiO2-P25 under simulated sunlight irradiation. The kinetics of MB photodegradation in the presence of the different photocatalysts could be properly described using a Langmuir–Hinshelwood (LH) model, for which the ZnO:Ce (2 at.%) sample exhibited the highest value of effective kinetic constant.

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The role of band alignment in p-type conductivity of Na-doped ZnMgO: Polar versus non-polar

Cited by 19 publications

References 22 publications

Enhanced photoluminescence of nonpolar p-type ZnO film by surface plasmon resonance and electron transfer

Enhanced photoluminescence of nonpolar p-type ZnO film by surface plasmon resonance and electron transfer

Polar and Non-Polar Zn1−xMgxO:Sb Grown by MBE

In-Depth Structural and Optical Analysis of Ce-modified ZnO Nanopowders with Enhanced Photocatalytic Activity Prepared by Microwave-Assisted Hydrothermal Method

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