Optical Energy Gap of Ti:Al2O3 Single Crystals

2011 ◽  
Vol 11 (5) ◽  
pp. 888-891 ◽  
Author(s):  
Hamdan Hadi Kusuma ◽  
Zuhairi Ibrahim ◽  
Mohamad Khairi Saidin
Keyword(s):  
Single Crystals ◽  
Energy Gap ◽  
Optical Energy Gap ◽  
Optical Energy

Optical properties of Ho3+-, Er3+-, and Tm3+-doped BaIn2S4 and BaIn2Se4 single crystals

2002 ◽  
Vol 17 (8) ◽  
pp. 2147-2152 ◽  
Author(s):  
Sang-An Park ◽  
Mi-Yang Kim ◽  
Wha-Tek Kim ◽  
Moon-Seog Jin ◽  
Sung-Hyu Choe ◽  
...  
Keyword(s):  
Single Crystals ◽  
Energy Gap ◽  
Photoluminescence Spectra ◽  
Optical Energy Gap ◽  
Acceptor Pair ◽  
Chemical Transport Reaction ◽  
Transport Reaction ◽  
Optical Energy ◽  
Broad Emission ◽  
Donor Acceptor

BaIn2S4, BaIn2S4:Ho3+, BaIn2S4:Er3+, BaIn2S4:Tm3+, BaIn2Se4, BaIn2Se4:Ho3+, BaIn2Se4:Er3+, and BaIn2Se4:Tm3+ single crystals were grown by the chemical transport reaction method. The optical energy gap of the single crystals was found to be 3.057, 2.987, 2.967, 2.907, 2.625, 2.545, 2.515, and 2.415 eV, respectively, at 11 K. The temperature dependence of the optical energy gap was well fitted by the Varshni equation. Broad emission peaks were observed in the photoluminescence spectra of the single crystals. They were assigned to donor–acceptor pair recombination. Sharp emission peaks were observed in the doped single crystals. They were attributed to be due to radiation recombination between the Stark levels of the Ho3+, Er3+, and Tm3+ ions sited in C1 symmetry.

scholarly journals Temperature Dependence of the Optical Band Gap and Optical Parameters of Tetramethyl Ammonium Tetrachlorozincate (TMA)2ZnCl4 single Crystals Around the Normal and Incommensurate Phase Transitions

2015 ◽  
Vol 9 (1) ◽  
pp. 162-172 ◽  
Author(s):  
A. Abu El-Fadl ◽  
A.M. Nashaat
Keyword(s):  
Single Crystals ◽  
Room Temperature ◽  
Energy Gap ◽  
Optical Transition ◽  
Incommensurate Phase ◽  
Spectral Studies ◽  
Optical Parameters ◽  
Optical Energy Gap ◽  
Optical Energy ◽  
Increasing Temperature

Single crystals of tetramethylammonium tetrachlorozincate [N(CH3)4]ZnCl4 abbreviated hereafter as (TMA)2ZnCl4 were grown using the slow evaporation technique at 315 K. The X-ray powder diffraction patterns indicated that [N(CH)]ZnCl belongs to the orthorhombic system with Pmcn symmetry at room temperature. The lattice constants are found to be a= 12.360 Å, b= 15.687 Å and c= 8.985 Å. The values were in good agreement with the values in previous studies. Ultraviolet–visible–near-infrared (UV–Vis–NIR) spectral studies were carried out in the temperature range 276–307 K. This range of temperature involves two phase transition temperatures (Ti=296 K) from normal (parent) to incommensurate phase and (T=279 K) from incommensurate to commensurate-ferroelectric phase. The cut off wavelength was found to be 195.016 nm at room temperature. The optical transmittance increases with increasing temperature, and the cut off shifts to higher wavelengths. Analysis reveals that the type of optical transition is the indirect allowed one. The optical energy gap (Eg) has the value of 5.903 eV at room temperature. The value of optical energy gap (Eg) decreases with increasing temperature. The changes in the values of the cut off wavelength and optical energy gap (Eg) with changing the temperature were found to take different rates at the two phases under study, besides anomalous takes place at Ti and Tc. The absorption coefficient (α) as a function of the incident photon energy shows an exponential behavior near the absorption edge which suggests that the Urbach rule is obeyed and indicated the formation of a band tail. Urbach parameters were calculated at different temperatures and the frequencies of effective phonons and electron–phonon interaction constants were determined for various phases.

Temperature Dependence of Optical Energy Gap of Gallium Selenide

2001 ◽  
Vol 8 (3-4) ◽  
pp. 251-259 ◽  
Author(s):  
M. Kepinska ◽  
M. Nowak ◽  
Z. Kovalyuk ◽  
R. Murri
Keyword(s):  
Temperature Dependence ◽  
Energy Gap ◽  
Gallium Selenide ◽  
Optical Energy Gap ◽  
Optical Energy

T(Z) diagram and optical energy gap values of (AgIn)2(1–z)(CdIn2)zTe4 alloys

1994 ◽  
Vol 144 (2) ◽  
pp. 311-316 ◽  
Author(s):  
R. Cadenas ◽  
M. Quintero ◽  
J. C. Woolley
Keyword(s):  
Energy Gap ◽  
Optical Energy Gap ◽  
Optical Energy ◽  
Gap Values

Study the Effect of the Volumetric Ratio of Alq3 on the Optical and Structural Properties of the Alq3:NPD Blend for the UV Photodetector Applications

2021 ◽  
Vol 16 (2) ◽  
pp. 281-287
Author(s):  
Alaa Y. Mahmoud
Keyword(s):  
Structural Properties ◽  
Active Layer ◽  
Energy Gap ◽  
Optical Energy Gap ◽  
Uv Photodetector ◽  
Optical Energy ◽  
Uv Photodetectors ◽  
Energy Bandgap ◽  
Xrd Patterns ◽  
Optical Energy Bandgap

The effect of the volumetric ratio of the tris(8-hydroxyquinoline) aluminum (Alq3) on its blend with the N,N'-Di [(1-naphthyl)-N,N'-diphenyl]-(1,1'-biphenyl)-4,4'-diamine (NPD) (Alq3:NPD) is investigated and optimized for the UV photodetectors fabrication. The optical and structural properties of Alq3:NPD blend with different volumetric ratios 1:1, 2:1, and 3:1 is studied in the context of the absorbance, transmittance, optical energy gap and XRD patterns. Results show that the absorbance is increased by 11% at A = 260 nm with the increase in the volumetric ratio. In contrast, the optical energy bandgap that is extrapolated from the Tauc’s plot is decreased with the increase in the volumetric ratio, and the 2:1 ratio shows the lowest energy in the UV region. In terms of the XRD investigation, the 2:1 volumetric ratio shows the highest intensity for the crystallinity peak at 36.6°. The fabricated photodetector with a different volumetric ratio of the active layer Alq3:NPD blend shows the best performance with the ratio 2:1.

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