scholarly journals Electronic, Optical, and Thermoelectric Properties of Bulk and Monolayer Germanium Tellurides

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1290
Author(s):  
Wenny V. Sinambela ◽  
Sasfan A. Wella ◽  
Fitri S. Arsyad ◽  
Nguyen Tuan Hung ◽  
Ahmad R. T. Nugraha
Keyword(s):  
Thermoelectric Properties ◽  
Near Infrared ◽  
Quantum Confinement Effect ◽  
Transport Coefficients ◽  
Wide Band ◽  
Wide Frequency Range ◽  
First Principles Calculations ◽  
Wide Band Gap ◽  
Electronic Band ◽  
Light Absorbers

Electronic, optical, and thermoelectric properties of germanium tellurides (GeTe) were investigated through a series of first-principles calculations of band structures, absorption coefficients, and thermoelectric transport coefficients. We consider bulk GeTe to consist of cubic and rhombohedral phases, while the two-dimensional (2D) GeTe monolayers can form as a 2D puckered or buckled honeycomb crystals. All of the GeTe variants in the bulk and monolayer shapes are excellent light absorbers in a wide frequency range: (1) bulk cubic GeTe in the near-infrared regime, (2) bulk rhombohedral GeTe and puckered monolayer GeTe in the visible-light regime, and (3) buckled monolayer GeTe in the ultraviolet regime. We also found specifically that the buckled monolayer GeTe exhibits remarkable thermoelectric performance compared to the other GeTe phases due to a combination of electronic band convergence, a moderately wide band gap, and unique 2D density of states from the quantum confinement effect.

Spectroscopic Analysis and Synthesis of Wide Band Gap CdS Quantum Dots Using Colloidal Synthesis Technique at Low Temperature

2009 ◽  
Vol 67 ◽  
pp. 191-196 ◽  
Author(s):  
Lubna Hashmi ◽  
M.S. Qureshi ◽  
R.N. Dubey ◽  
M.M. Malik ◽  
Ishrat Alim ◽  
...  
Keyword(s):  
Low Temperature ◽  
Band Gap ◽  
Spectroscopic Analysis ◽  
Quantum Confinement Effect ◽  
Wide Band ◽  
Colloidal Synthesis ◽  
Visible Range ◽  
Wide Band Gap ◽  
Synthesis Technique ◽  
Analysis And Synthesis

A broad range of II-VI materials has been investigated in order to produce light in the full visible range for optoelectronic applications. The present investigation was carried out for the spectroscopic analysis and synthesis of wide band gap cadmium sulfide nanoparticles. Large-band gap semiconductors have the added advantage in that; they can support higher electric field before breaking down, which means that they can be used for high-power electronic devices.Synthesis has been carried out using colloidal synthesis technique at low temperature. The size, stabilization and optical properties were studied using UV-vis Spectrophotometer and Spectroflourometer. Further, the structural studies of synthesized powder were carried out using X-ray diffraction technique; which also confirms the formation of desired product. The capping ligand and the impurities present in the sample were characterized by Fourier transform infra red spectroscopy. Synthesized CdS powder dispersed in aqueous media gave the value of 193 nm for the onset wavelength using UV-vis spectrophotometer, which is significantly blue-shifted compared to bulk CdS and shows the quantum confinement effect. From the onset wavelength the radius of CdS quantum dot calculated using the Brus equation was found to be ca. 0.7 nm.

Wide Band Gap Al and In Co-doped ZnO Films for Near-Infrared Plasmonic Application

Plasmonics ◽  
2021 ◽  
Author(s):  
Soumya Kannoth ◽  
Packia Selvam Irulappan ◽  
Sandip Dhara ◽  
Sankara Narayanan Potty
Keyword(s):  
Band Gap ◽  
Near Infrared ◽  
Wide Band ◽  
Zno Films ◽  
Wide Band Gap ◽  
Doped Zno ◽  
Co Doped

Infrared Spectroscopy of Hydrogen in ZnO

2004 ◽  
Vol 813 ◽  
Author(s):  
M.D. Mccluskey ◽  
S.J. Jokela
Keyword(s):  
First Principles ◽  
Experimental Studies ◽  
Wide Band ◽  
Shallow Donor ◽  
Great Promise ◽  
Bulk Single Crystal ◽  
First Principles Calculations ◽  
Wide Band Gap ◽  
Theoretical Predictions ◽  
Good Agreement

ABSTRACTZinc oxide (ZnO) has shown great promise as a wide band gap semiconductor with optical, electronic, and mechanical applications. Recent first-principles calculations and experimental studies have shown that hydrogen acts as a shallow donor in ZnO, in contrast to hydrogen's usual role as a passivating impurity. The structures of such hydrogen complexes, however, have not been determined. To address this question, we performed vibrational spectroscopy on bulk, single-crystal ZnO samples annealed in hydrogen (H2) or deuterium (D2) gas. Using infrared (IR) spectroscopy, we have observed O-H and O-D stretch modes at 3326.3 cm−1 and 2470.3 cm−1 respectively, at a sample temperature of 14 K. These frequencies are in good agreement with the theoretical predictions for hydrogen and deuterium in an antibonding configuration, although the bond-centered configuration cannot be ruled out. The IR-active hydrogen complexes are unstable, however, with a dissocation barrier on the order of 1 eV.

Magnetic ions in wide band gap semiconductor nanocrystals for optimized thermoelectric properties

2014 ◽  
Vol 1 (1) ◽  
pp. 81-86 ◽  
Author(s):  
Chong Xiao ◽  
Kun Li ◽  
Jiajia Zhang ◽  
Wei Tong ◽  
Youwen Liu ◽  
...  
Keyword(s):  
Band Gap ◽  
Thermoelectric Properties ◽  
Semiconductor Nanocrystals ◽  
Wide Band ◽  
Wide Band Gap ◽  
Magnetic Ions

Transition of wide-band gap semiconductor h-BN(BN)/P heterostructure via single-atom-embedding

2020 ◽  
Vol 8 (28) ◽  
pp. 9755-9762 ◽  
Author(s):  
Itsuki Miyazato ◽  
Tanveer Hussain ◽  
Keisuke Takahashi
Keyword(s):  
Boron Nitride ◽  
Band Gap ◽  
First Principles ◽  
Wide Band ◽  
Band Gaps ◽  
Single Atom ◽  
First Principles Calculations ◽  
Optoelectronic Materials ◽  
Wide Band Gap

The band gaps in boron nitride/phosphorene (h-BN/P) heterostructures are investigated by single-atom-embedding via first principles calculations. The modified heterostructures are potential optoelectronic materials with tunable band gaps.

scholarly journals Thermoelectric properties of the 3C, 2H, 4H, and 6H polytypes of the wide-band-gap semiconductors SiC, GaN, and ZnO

AIP Advances ◽  
2015 ◽  
Vol 5 (9) ◽  
pp. 097204 ◽  
Author(s):  
Zheng Huang ◽  
Tie-Yu Lü ◽  
Hui-Qiong Wang ◽  
Jin-Cheng Zheng
Keyword(s):  
Band Gap ◽  
Thermoelectric Properties ◽  
Wide Band ◽  
Wide Band Gap ◽  
Wide Band Gap Semiconductors

Potential of Nano-Sized Rare Earth Fluorides in Optical Applications

2005 ◽  
Vol 106 ◽  
pp. 93-102 ◽  
Author(s):  
Ulrich H. Kynast ◽  
Marina M. Lezhnina ◽  
H. Kätker
Keyword(s):  
Rare Earth ◽  
Near Infrared ◽  
Vacuum Ultraviolet ◽  
Wide Band ◽  
Rare Earth Ions ◽  
Wide Band Gap ◽  
Coordination Numbers ◽  
Porous Matrices ◽  
Optical Applications ◽  
Rare Earth Fluorides

Rare earth fluorides are a class of materials with a high potential for optical applications. Fluoride lattices allow high coordination numbers for the hosted rare earth ions, but the high ionicity of the rare earth to fluorine bond leads to a wide band gap and very low vibrational energies. These two essential factors, in particular, contribute to their practicality for use in optical applications based on vacuum ultraviolet (VUV) and near infrared (NIR) excitation. The preparation and optical characteristics of rare earth fluoride nanoparticles and their embedding in polymeric, glassy or porous matrices are very promising for the eventual manufacture of transparent hybrid materials. Recent attempts to control the size of these particles down to the nano-scale and, at the same time, maintaining the performance of their macroscopic counterparts, indicate accessibility of hitherto unrealized optical properties and applications.

Electronic Structures of Wide Band-Gap (AlN)m(GaN)n[001] Superlattices

1995 ◽  
Vol 395 ◽  
Author(s):  
Z.-J. Tian ◽  
M.W.C. Dharma-Wardana ◽  
L.J. Lewis
Keyword(s):  
Band Gap ◽  
Electronic Band Structure ◽  
Wide Band ◽  
Orbital Method ◽  
Full Potential ◽  
Wide Band Gap ◽  
Electronic Band ◽  
Level Shifts ◽  
Direct Band ◽  
Near Term

ABSTRACTWide bandgap III-V nitrides, such as GaN and AlN, have become topical in the near-term technology of blue lasers. We report detailed electronic band-structure calculations for (AlN)m(GaN)n [001] zinc-blende superlattices (SL), with m + n ≤ 12, using the all-electron full-potential linear-muffin-tin-orbital method. For n ≥ 3, the SL are found to have a direct band gap. For n ≤ 2 and m ≥ 3, all the band gaps are indirect. In ultrathin SL, m ≤ 3 and n ≤ 2, only (m, n)= (3,1) is found to have an indirect gap. The band offsets are estimated by calculating the core-level shifts of nitrogen atoms in the central planes of the GaN and A1N layers. The calculated densities of states, electron- and hole- effective masses (m), etc., as a function of m and n, are reported; a remarkable dependence of m on the number of layers is revealed.

First principles study of defects in solid electrolyte lithium thiophosphate Li7P3S11

2011 ◽  
Vol 1331 ◽  
Author(s):  
Ka Xiong ◽  
Weichao Wang ◽  
Roberto Longo Pazos ◽  
Kyeongjae Cho
Keyword(s):  
Electronic Structure ◽  
Solid Electrolyte ◽  
Band Gap ◽  
Electronic Properties ◽  
First Principles ◽  
Wide Band ◽  
Ion Conductivity ◽  
First Principles Calculations ◽  
Wide Band Gap ◽  
Formation Energies

ABSTRACTWe investigate the electronic structure of interstitial Li and Li vacancy in Li7P3S11 by first principles calculations. We find that Li7P3S11 is a good insulator with a wide band gap of 3.5 eV. We find that the Li vacancy and interstitial Li+ ion do not introduce states in the band gap hence they do not deteriorate the electronic properties of Li7P3S11. The calculated formation energies of Li vacancies are much larger than those of Li interstitials, indicating that the ion conductivity may arise from the migration of interstitial Li.

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