Anomalous luminescent properties in ZnO and SrAl2O4 composites

RSC Advances ◽  
2014 ◽  
Vol 4 (69) ◽  
pp. 36765-36770
Author(s):  
V. P. Singh ◽  
P. Mohanty ◽  
S. P. Lochab ◽  
Chandana Rath
Keyword(s):  
Monoclinic Phase ◽  
Hexagonal Phase ◽  
Energy Band Diagram ◽  
Luminescent Properties ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Band Diagram ◽  
Edge Emission ◽  
Defect Band ◽  
Band Emission

We showed a phase transformation from high temperature hexagonal phase to most stable monoclinic phase of SrAl2O4 by incorporating 20% of ZnO in ZnO and SrAl2O4 composite (Singh et al. 2014 Dalton Transactions). The composite with monoclinic phase further showed the intense near band edge emission and defect band emission corresponding to ZnO without any signature of SrAl2O4 in PL spectra. An energy band diagram responsible for defect band emission is proposed for the composites.

Characterization of GaN Films on Sapphire by Cathodoluminescence

1996 ◽  
Vol 449 ◽  
Author(s):  
L.-L. Chao ◽  
G. S. Cargill ◽  
C. Kothandaraman
Keyword(s):  
Deep Level ◽  
Luminescent Properties ◽  
Deep Level Emission ◽  
Band Edge ◽  
Near Band Edge Emission ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Luminescence Efficiency ◽  
Si Doped

ABSTRACTCathodoluminescence (CL) spectroscopy and microscopy were used to study the luminescent properties of a variety of GaN films, both Si-doped and unintentionally-doped, grown on sapphire substrates. A narrow and intense near band-edge emission was found in the CL spectrum of each film examined, and deep-level emission was also observed for some of the films. The luminescence efficiency of near band-edge emission increased with a faster rate than that of deep-level emission when the pumping current was increased. Spatial nonuniformities of luminescence were observed in monochromatic CL microscopy, and microstructures were observed in scanning electron microscopy. No correlations between luminescence features and microstructural features were seen. Degradation of near band-edge luminescence was observed, accompanied by growth of deep-level emission.

scholarly journals Influence of the First Preparation Steps on the Properties of GaN Layers Grown on 6H-SiC by MBE

1999 ◽  
Vol 4 (S1) ◽  
pp. 310-315 ◽  
Author(s):  
R. Lantier ◽  
A. Rizzi ◽  
D. Guggi ◽  
H. Lüth ◽  
B. Neubauer ◽  
...  
Keyword(s):  
Substrate Surface ◽  
Free Exciton ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Rocking Curve ◽  
A Value ◽  
Dislocations Density ◽  
Aln Buffer ◽  
Atomically Flat

The Gan heteroepitaxy on 6H-SiC is affected by the bad morphology of the substrate surface. We performed a hydrogen etching at 1550oC on the 6H-SiC(0001) substrates to obtain atomically flat terraces. An improvement of the structural properties of GaN grown by MBE on such substrates after deposition of a LT-AlN buffer layer is observed. A value of less than 220 arcsec of the FWHM of the XRD rocking curve, showing a reduced screw dislocations density, is comparable with the best results reported until now for thick GaN samples. Photoluminescence showed a structured near band edge emission spectrum with evidence of the A, B and C free exciton recombinations.

Photoluminescence and Raman Studies of Annealed ZnO Nanostructures

2012 ◽  
Vol 501 ◽  
pp. 179-183 ◽  
Author(s):  
Siti Khadijah Mohd Bakhori ◽  
Chuo Ann Ling ◽  
Shahrom Mahmud
Keyword(s):  
Optical Signal ◽  
High Mode ◽  
Raman Shift ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Zno Nanostructures ◽  
Zno Nanostructure ◽  
Band Emission ◽  
Crystallite Sizes ◽  
Tem Microscopy

The influence of annealing on the optical properties of as-grown ZnO nanostructures prepared in pellets has been investigated by photoluminescence (PL) and Raman spectroscopy. The annealing temperatures of ZnO nanostructure at 600°C, 650°C and 700 °C were conducted in oxygen (O2) and nitrogen (N2) ambient. The near band edge emission (NBE) of samples recorded in the PL spectra demonstrates significant changes on optical signal whereby the NBE is redshifted after O2 annealed and became slightly higher in N2 annealed. Apart from that, weak green luminescence (GL) namely deep band emission (DBE) is observed centre at 532.95 nm (2.23 eV) and 511.00 nm (2.42 eV) for annealed in O2 and N2 respectively, whereas lower DBE observed in as-grown ZnO. On the other hand, Raman shift reveal the phonon mode of the ZnO nanostructures and the E2 (high) mode were downshifted as annealed in O2 ambient, and upshifted in N2 ambient. The downshift and upshift of the E2 (high) mode are correlated to tensile and compressive stress. Moreover the crystallite sizes were calculated from FWHM of XRD and TEM microscopy reveals the nanoplates structure of ZnO nanostructures.

Stable enhancement of near-band-edge emission of ZnO nanowires by hydrogen incorporation

2010 ◽  
Vol 21 (6) ◽  
pp. 065709 ◽  
Author(s):  
A Dev ◽  
R Niepelt ◽  
J P Richters ◽  
C Ronning ◽  
T Voss
Keyword(s):  
Zno Nanowires ◽  
Band Edge ◽  
Near Band Edge Emission ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Hydrogen Incorporation

Growth Spindle-Like ZnO Nanocrystalline Thin Films on Nickel Layers by Dc Magnetron Sputtering and its Thermal Annealing Properties

2011 ◽  
Vol 675-677 ◽  
pp. 1097-1100
Author(s):  
W. Wu ◽  
X.H. Xiao ◽  
T.C. Peng ◽  
C.Z. Jiang
Keyword(s):  
Thin Film ◽  
Magnetron Sputtering ◽  
Structural Features ◽  
Optical Quality ◽  
Zno Films ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Dc Magnetron Sputtering ◽  
Band Emission ◽  
Thin Film Layer

A novel spindle-like zinc oxide (ZnO) nanocrystalline thin film was successfully fabricated on Ni thin film layer by ultrahigh-vacuum dc magnetron sputtering. Then the as-grown films were annealed in air at various temperatures from 673 to 1073 K, the corresponding structural features and surface morphology were studied by X-ray diffraction (XRD) and field emission scanning electronic microscopy (FE-SEM). The results reveal that the dominant direction of grains movement changed from perpendicular to parallel to the film interfaces. A correlation of the band gap and photoluminescence (PL) properties of nanocrystalline ZnO films with particle size morphologies and strain was discussed. Especially, PL emission in UV range, which is due to near band edge emission is more intense in comparison with the green band emission (due to defect state) was observed in all samples, indicating a good optical quality of the deposited films.

Enhancement of the near-band-edge emission of CuI by Cl doping

2019 ◽  
Vol 205 ◽  
pp. 337-341 ◽  
Author(s):  
Fengrui Li ◽  
Mu Gu ◽  
Xiaolin Liu ◽  
Shuangqiang Yue ◽  
Jiajie Zhu ◽  
...  
Keyword(s):  
Band Edge ◽  
Near Band Edge Emission ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Edge Emission

Enhanced near-band-edge emission from a-plane ZnO thin films on SrTiO3 substrates

2015 ◽  
Vol 121 (1) ◽  
pp. 17-21 ◽  
Author(s):  
Guangheng Wu ◽  
Xiang Li ◽  
Meifeng Liu ◽  
Zhibo. Yan ◽  
Jun-Ming Liu
Keyword(s):  
Thin Films ◽  
Band Edge ◽  
Zno Thin Films ◽  
Near Band Edge Emission ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Edge Emission

Chemical Vapor Deposition of Porous GaN Particles on Silicon

2012 ◽  
Vol 18 (4) ◽  
pp. 905-911 ◽  
Author(s):  
Joan J. Carvajal ◽  
Oleksandr V. Bilousov ◽  
Dominique Drouin ◽  
Magdalena Aguiló ◽  
Francesc Díaz ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Band Edge ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Si Substrates ◽  
Internal Morphology ◽  
Simple Chemical

AbstractWe present a technique for the direct deposition of nanoporous GaN particles on Si substrates without requiring any post-growth treatment. The internal morphology of the nanoporous GaN particles deposited on Si substrates by using a simple chemical vapor deposition approach was investigated, and straight nanopores with diameters ranging between 50 and 100 nm were observed. Cathodoluminescence characterization revealed a sharp and well-defined near band-edge emission at ∼365 nm. This approach simplifies other methods used for this purpose, such as etching and corrosion techniques that can damage the semiconductor structure and modify its properties.

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