Effect of polycrystallinity on the optical properties of highly oriented ZnO grown by pulsed laser deposition

McGlynn, Enda

doi:10.1016/s0040-6090(03)01960-6

Cited by 5 publications

(9 citation statements)

References 13 publications

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“…Previous Raman and AFM measurements on these samples indicate that the unannealed sample has the smallest grain size and the largest surface roughness (standard deviation of ~ 10 nm) and that the grain size increases and the roughness decreases (to a value of ~ 3 nm) in the annealed samples [13,14]. The decrease in the intensity of excitonic features with decreasing grain size is a consequence of the increasing effects of electric fields due to charge trapping at grain boundaries in smaller grain samples, causing substantial exciton damping [13,14]. We also observe oscillatory structures at lower ("region I") and higher ("region III") energies.…”

Section: Resultsmentioning

confidence: 86%

“…The samples grown are nanocrystalline with a columnar grain structure with c-axis orientation and show evidence of strong electric field damping of the free-exciton (FE) [13]. Some samples were further annealed in O 2 (0.3 mbar) at temperatures of 400°C and 500°C respectively in the growth chamber immediately after deposition, leading to a consistent increase in grain size (30 → 80 nm) and reduction in FE damping with annealing temperature [13,14]. The single-crystal material was purchased from the EaglePicher Corporation, and was grown using the Seeded Vapor Phase Transport (SVPT) method.…”

Section: Methodsmentioning

confidence: 99%

“…The single-crystal material was purchased from the EaglePicher Corporation, and was grown using the Seeded Vapor Phase Transport (SVPT) method. More details of the reflectance measurements are given in [10,13]. No observable change is seen with different polarisations of the incident radiation.…”

Section: Methodsmentioning

confidence: 99%

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Study of exciton–polariton modes in nanocrystalline thin films of ZnO using reflectance spectroscopy

Fryar¹,

McGlynn²,

Henry³

et al. 2005

Nanotechnology

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We report detailed reflectance studies of the exciton-polariton structure of thin-film nanocrystalline ZnO at low temperatures and compare these data to bulk crystal behaviour. The reflectance spectra are fit using a two-band dielectric response function with a number of different models involving reflected waves in the thin-film and/or excitonic dead-layers. We present matrix forms for the solution of these models, enabling computation of the reflected intensity and other field components. The reflectance of nanocrystalline ZnO differs substantially from that of bulk material, with Fabry-Perot oscillations at energies below the transverse A exciton and above the longitudinal B exciton. Between these energies we see no evidence of anomalous waves because the strong interaction of the damped exciton with the photon leads to polaritons with substantial damping such that the Fabry-Perot oscillations are eliminated. Good agreement is found between the model and data and the importance of the polariton viewpoint in understanding the reflectance data of nanocrystalline material is clearly seen. The fits provide parameter values that can be compared to bulk crystal parameters, providing a method for quantitative analysis of the films and their potential for applications such as thin-film random lasing or polariton lasing in microcavities.

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Section: Resultsmentioning

confidence: 86%

Section: Methodsmentioning

confidence: 99%

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Study of exciton–polariton modes in nanocrystalline thin films of ZnO using reflectance spectroscopy

Fryar¹,

McGlynn²,

Henry³

et al. 2005

Nanotechnology

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“…For example, strain effects in thin films can significantly alter the exciton energies and bandgap values, as has been reported for ZnO thin films. 23 CuCl reflectance spectroscopy (conducted in a cryostat in a He atmosphere) is particularly well suited to studies of CuCl due to the hygroscopic nature of the material because one can control and indeed reduce=eliminate the normal atmospheric exposure-related decay of the samples even over the course of extended measurements. …”

Section: Discussionmentioning

confidence: 99%

Study of exciton-polariton modes in nanocrystalline thin films of CuCl using reflectance spectroscopy

Foy

McGlynn

Cowley

et al. 2012

Journal of Applied Physics

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Photoluminescence study of magnetic spin clusters and their temperature evolution in Cd0.70Mn0.30Te spinglass compound J. Appl. Phys. 112, 093715 (2012) Excitonic luminescence in two-dimensionally confined layered sulfide oxides Appl. Phys. Lett. 101, 191901 (2012) Excitons imaging in hybrid organic-inorganic films J. Appl. Phys. 112, 093105 (2012) Bound and anti-bound biexciton in site-controlled pyramidal GaInAs/GaAs quantum dots Appl. Phys. Lett. 101, 191101 (2012) Vanadium bound exciton luminescence in 6H-SiC Appl. Phys. Lett. 101, 151903 (2012) Additional information on J. Appl. Phys. CuCl thin films grown on (100) Si by thermal evaporation are studied using reflectance spectroscopy. The reflectance spectra in the near UV spectral range close to the CuCl bandgap are modeled using a dielectric response function based on an exciton-polariton response with various models involving dead layers and reflected waves in the thin film. The exciton-polariton structure obtained is compared to other studies of bulk CuCl crystals. These different models are analyzed using a matrix-based approach and they yield theoretical spectra of reflected intensity. The fits provide parameter values which can be compared to bulk data known for CuCl and provide a nondestructive means of quantitative analysis of CuCl thin films. The best models are shown to match the experimental data quite well, with the closest fits produced when thin film front and rear interfaces are included. This model also accurately simulates the Fabry-Perot fringes present at energies lower than the Z 3 free exciton position in CuCl (at 3.272 eV). V C 2012 American Institute of Physics. [http://dx

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“…The major research efforts have been focused on investigations and fabrication of ZnO related nanostructures, the p-type doping, and optoelectronic devices based on ZnO. The ZnO epilayers and nanostructures have been grown on various types of substrates by different techniques, such as molecular beam epitaxy (MBE), 1-4 metal-organic vapor phase epitaxy or metal organic chemical vapor deposition (MOCVD), [5][6][7][8][9][10] pulsed laser deposition (PLD), 11,12 the vapour-liquid-solid (VLS) catalytic growth technique, [13][14][15] magnetron sputtering, 16,17 and low temperature chemical solutions. 18,19 There are also great efforts to grow p-type layers of ZnO and ZnO based heterostructures (such as ZnMgO/ZnO, ZnBeO/ZnO, and ZnMnO/ZnO).…”

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confidence: 99%

Properties of shallow donors in ZnMgO epilayers grown by metal organic chemical vapor deposition

Zhao¹,

Liu²,

Holtz³

2014

Journal of Applied Physics

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Influence of thermally diffused aluminum atoms from sapphire substrate on the properties of ZnO epilayers grown by metal-organic chemical vapor deposition J. Vac. Sci. Technol. A 29, 03A106 (2011) The grown samples were investigated by x-ray photoelectron spectroscopy and photoluminescence. The magnesium (Mg) concentration was varied between 0% and 3% in order to study the properties of shallow donors. The free and donor bound excitons could be observed simultaneously in our high quality Zn 1Àx Mg x O epilayers in the photoluminescence spectra. The results indicate that both built-in strain and Mg-concentration influence the donor exciton binding energy. It clearly shows that the donor exciton binding energy decreases with increasing Mg-concentration and with increasing built-in strain. Furthermore, the results indicate that the donor bound exciton transition energy increases with decreasing strength of the built-in strain if the Mg-concentration is kept the same in the Zn 1Àx Mg x O epilayers. V C 2014 AIP Publishing LLC.

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Effect of polycrystallinity on the optical properties of highly oriented ZnO grown by pulsed laser deposition

Cited by 5 publications

References 13 publications

Study of exciton–polariton modes in nanocrystalline thin films of ZnO using reflectance spectroscopy

Study of exciton–polariton modes in nanocrystalline thin films of ZnO using reflectance spectroscopy

Study of exciton-polariton modes in nanocrystalline thin films of CuCl using reflectance spectroscopy

Properties of shallow donors in ZnMgO epilayers grown by metal organic chemical vapor deposition

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