Temperature-dependent optical band gap of the metastable zinc-blende structure β-GaN

1994 ◽  
Vol 50 (12) ◽  
pp. 8433-8438 ◽  
Author(s):  
G. Ramírez-Flores ◽  
H. Navarro-Contreras ◽  
A. Lastras-Martínez ◽  
R. C. Powell ◽  
J. E. Greene
Keyword(s):  
Band Gap ◽  
Optical Band Gap ◽  
Temperature Dependent ◽  
Zinc Blende ◽  
Zinc Blende Structure

scholarly journals Temperature-Dependent Optical Band Gap in CsPbBr3, MAPbBr3, and FAPbBr3 Single Crystals

2020 ◽  
Vol 11 (7) ◽  
pp. 2490-2496 ◽  
Author(s):  
Giovanni Mannino ◽  
Ioannis Deretzis ◽  
Emanuele Smecca ◽  
Antonino La Magna ◽  
Alessandra Alberti ◽  
...  
Keyword(s):  
Band Gap ◽  
Single Crystals ◽  
Optical Band Gap ◽  
Temperature Dependent

scholarly journals Thermal, Electrical, and Optical Properties of Synthesized (1E, 2E)-(4-bromophenyl)(hydroxyimino)acetaldehyde Oxime Complexes

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Emin Karapinar ◽  
Orhan Karabulut ◽  
Nazan Karapinar
Keyword(s):  
Band Gap ◽  
Optical Band Gap ◽  
Conductivity Measurements ◽  
Energy Band Gap ◽  
Temperature Dependent ◽  
Electrical And Optical Properties ◽  
Analysis Techniques ◽  
Temperature Dependent Conductivity ◽  
Ft Ir ◽  
Thermal Analysis Techniques

The (1E, 2E)-(4-bromophenyl)(hydroxyimino)acetaldehyde oxime complexes, [ML2], M = Co(II), Cu(II), and Ni(II), were synthesized and characterized by elemental analysis, magnetic susceptibility, FT-IR spectra, and thermal analysis techniques. The optical band gap of this ligand and its complexes were determined by UV-vis spectrophotometer in the wavelength range 300–800 nm. A decrease in the energy band gap of the [CoL2], [NiL2], and [CuL2] complexes has been observed compared with LH ligand. Temperature-dependent conductivity measurements showed that all samples behave like semiconductor. Activation energies calculated from Arrhenius plots showed that the conduction occurs via both intramolecular and the intermolecular processes.

scholarly journals Temperature-dependent optical constants of monolayer $${\text {MoS}}_2$$, $${\text {MoSe}}_2$$, $${\text {WS}}_2$$, and $${\text {WSe}}_2$$: spectroscopic ellipsometry and first-principles calculations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hsiang-Lin Liu ◽  
Teng Yang ◽  
Jyun-Han Chen ◽  
Hsiao-Wen Chen ◽  
Huaihong Guo ◽  
...  
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Room Temperature ◽  
Optical Constants ◽  
Near Infrared ◽  
Optical Band Gap ◽  
Transition Metal Dichalcogenides ◽  
First Principles Calculations ◽  
Temperature Dependent ◽  
Metal Dichalcogenides

Abstract The temperature-dependent ($$T = 4.5 \, \hbox {-} \, 500 \, \hbox {K}$$ T = 4.5 - 500 K ) optical constants of monolayer $${\text {MoS}}_2$$ MoS 2 , $${\text {MoSe}}_2$$ MoSe 2 , $${\text {WS}}_2$$ WS 2 , and $${\text {WSe}}_2$$ WSe 2 were investigated through spectroscopic ellipsometry over the spectral range of 0.73–6.42 eV. At room temperature, the spectra of refractive index exhibited several anomalous dispersion features below 800 nm and approached a constant value of 3.5–4.0 in the near-infrared frequency range. With a decrease in temperature, the refractive indices decreased monotonically in the near-infrared region due to the temperature-dependent optical band gap. The thermo-optic coefficients at room temperature had values from $$6.1 \times 10^{-5}$$ 6.1 × 10 - 5 to $$2.6 \times 10^{-4} \, \hbox {K}^{-1}$$ 2.6 × 10 - 4 K - 1 for monolayer transition metal dichalcogenides at a wavelength of 1200 nm below the optical band gap. The optical band gap increased with a decrease in temperature due to the suppression of electron–phonon interactions. On the basis of first-principles calculations, the observed optical excitations at 4.5 K were appropriately assigned. These results provide basic information for the technological development of monolayer transition metal dichalcogenides-based photonic devices at various temperatures.

Organometallic Vapor Phase Epitaxial Growth of ZnGeAs2 and (ZnGeAs2)xGe1−x on GaAs

1988 ◽  
Vol 144 ◽  
Author(s):  
G. S. Solomon ◽  
J. B. Posthill ◽  
M. L. Timmons
Keyword(s):  
Single Crystal ◽  
Band Gap ◽  
Lattice Constant ◽  
Vapor Phase ◽  
Gaas Substrate ◽  
Lattice Mismatch ◽  
Chalcopyrite Structure ◽  
Zinc Blende ◽  
Indirect Band Gap ◽  
Zinc Blende Structure

ABSTRACTEpitaxial single crystal (001) chalcopyrite-structure ZnGeAs2 and single crystal (100) zinc blende-structure (ZnGeAs2)xGe1−x alloys have been grown by organometallic vapor phase epitaxy on (100) GaAs. Selected area electron diffraction was used to determine the crystal structure for several Zn:Ge molar flow ratios. Bulk chemical composition was determined by electron microprobe and correlated to crystal lattice constants obtained from x-ray diffraction. Due to the lattice mismatch between chalcopyrite-structure ZnGeAs2 and the GaAs substrate, the epitaxy is elastically strained, compressing the a-lattice constant and elongating the c-lattice constant. Optical absorption and transmission spectroscopy indicate the zinc-blende-structure material has an indirect band gap of approximately 0.6 eV, whereas the chalcopyrite ZnGeAs2 has a direct band gap of 1.15 eV. Secondary ion mass spectroscopy reveals significant Zn diffusion into the GaAs substrate if the Zn:Ge molar flow ratio exceeds the ratio required for stoichiometric chalcopyrite-structure crystal growth.

Raman Scattering and Photoluminescence of Spontaneously Ordered Ga0.5In0.5P Alloy

1996 ◽  
Vol 452 ◽  
Author(s):  
G. H. Li ◽  
Z. X. Liu ◽  
H. X. Han ◽  
Z. P. Wang ◽  
J. R. Dong ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Band Gap ◽  
Room Temperature ◽  
Band Gaps ◽  
Photoluminescence Spectra ◽  
Zinc Blende ◽  
Gaas Substrates ◽  
Ordered Alloys ◽  
Direct Band ◽  
Zinc Blende Structure

AbstractSamples of the spontaneously ordered Ga0.5In0.5P alloys were grown by the MOCVD method on [001]-oriented GaAs substrates. The thickness of the epitaxal layer is about 2 μm. Raman scattering and photoluminescence spectra have been measured at room temperature. The result from photoluminescence measurement indicates that the direct-band gaps of the spontaneously ordered samples are lower than that of the disordered sample. Three scattering peaks have been observed in the Raman spectra, corresponding to the GaP-like LO, InP-like LO and InP-like TO modes in the alloys, respectively. The frequencies of the GaP- and InP-like LO modes increase with the decrease of the band-gap of the ordered alloys. It is related to the formation of the (GaP)1/(InP)1 monolayer superlattice along [111] direction in the ordered alloys. The polarization properties of the ordered alloys are similar to those of the bulk III-V semiconductors with the zinc-blende structure.

Stability Investigation in the Optical Properties of Thermally Evaporated Ge5Se95-x Znx Thin Films

2015 ◽  
Vol 7 (3) ◽  
pp. 1923-1930
Author(s):  
Austine Amukayia Mulama ◽  
Julius Mwakondo Mwabora ◽  
Andrew Odhiambo Oduor ◽  
Cosmas Mulwa Muiva ◽  
Boniface Muthoka ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Band Gap ◽  
Thermal Evaporation ◽  
Optical Transition ◽  
Bulk Material ◽  
Band Gap Energy ◽  
Optical Absorbance ◽  
Gap Energy ◽  
Constituent Elements

 Selenium-based chalcogenides are useful in telecommunication devices like infrared optics and threshold switching devices. The investigated system of Ge5Se95-xZnx (0.0 ≤ x ≤ 4 at.%) has been prepared from high purity constituent elements. Thin films from the bulk material were deposited by vacuum thermal evaporation. Optical absorbance measurements have been performed on the as-deposited thin films using transmission spectra. The allowed optical transition was found to be indirect and the corresponding band gap energy determined. The variation of optical band gap energy with the average coordination number has also been investigated based on the chemical bonding between the constituents and the rigidity behaviour of the system’s network.

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