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.

Photoluminescence spectra of undoped and Sm3+-doped BaAl2S4 and BaAl2Se4 single crystals

2001 ◽  
Vol 16 (5) ◽  
pp. 1520-1524 ◽  
Author(s):  
Moon-Seog Jin ◽  
Choong-Il Lee ◽  
Chang-Sun Yoon ◽  
Chang-Dae Kim ◽  
Jae-Mo Goh ◽  
...  
Keyword(s):  
Single Crystals ◽  
Energy Levels ◽  
Photoluminescence Spectra ◽  
Acceptor Pair ◽  
Chemical Transport Reaction ◽  
Ionic Radii ◽  
Transport Reaction ◽  
Broad Emission ◽  
Electron Transitions ◽  
Donor Acceptor

Undoped and Sm3+-doped BaAl2S4 and BaAl2Se4 single crystals were grown by the chemical transport reaction method. The optical energy band gaps of the BaAl2S4 and BaAl2Se4 were found to be 4.10 and 3.47 eV, respectively, at 5 K. In their photoluminescence spectra measured at 5 K, broad emission peaks at 459 and 601 nm appeared in the BaAl2S4 and at 486 and 652 nm in the BaAl2Se4. These emissions are assigned to donor–acceptor pair recombinations. Sharp emission peaks were observed in the Sm3+-doped BaAl2S4 and BaAl2Se4 single crystals at 5 K. Taking into account the ionic radii of the cations and Sm3+, these sharp emission peaks are attributed to the electron transitions between the energy levels of Sm3+ substituting with the Ba site.

Photoluminescence spectra of Zn1−xCdxAl2Se4-4xS4x single crystals

2000 ◽  
Vol 15 (12) ◽  
pp. 2690-2694 ◽  
Author(s):  
Sung-Hyu Choe ◽  
Chang-Sun Yoon ◽  
Moon-Seog Jin ◽  
Seung-Cheol Hyun ◽  
Chang Dae Kim ◽  
...  
Keyword(s):  
Single Crystals ◽  
Emission Band ◽  
Energy Gap ◽  
Visible Region ◽  
Chalcopyrite Structure ◽  
Broad Emission Band ◽  
Photoluminescence Spectra ◽  
Chemical Transport Reaction ◽  
Transport Reaction ◽  
Optical Energy

We investigated the photoluminescence as well as the crystal structure and optical energy gaps of the Zn1-xCdxAl2Se4-4xS4x solid solution system based on the Al-related compounds of ZnAl2Se4, ZnAl2S4, CdAl2Se4, and CdAl2S4. The single crystals of the system with 0.0 ≤ x ≤ 1.0 were grown by the chemical transport reaction technique. The Zn1-xCdxAl2Se4-4xS4x crystallizes in a defect chalcopyrite structure for a whole composition and has an optical energy gap ranging from 3.525 to 3.577 eV at 13 K. The photoluminescence spectra at 13 K showed a strong emission band in the blue spectral region and a weak broad emission band in the visible region due to donor–acceptor pair recombination. The composition and temperature dependence of these bands were examined in the investigated regions. The simple energy band scheme for the radiative mechanisms of the Zn1-xCdxAl2Se4-4xS4x is proposed on the basis of our experimental results along with photo-induced current transient spectroscopy measurements.

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

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
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