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.

Hydrogen Donors in ZnO

2005 ◽  
Vol 864 ◽  
Author(s):  
M.D. McCluskey ◽  
S.J. Jokela ◽  
W.M. Hlaing Oo
Keyword(s):  
First Principles ◽  
Experimental Studies ◽  
Shallow Donor ◽  
Great Promise ◽  
Bulk Single Crystal ◽  
First Principles Calculations ◽  
Electrical Measurements ◽  
Hydrogen Donors ◽  
Ir Signature ◽  
P Type

AbstractZinc oxide (ZnO) has shown great promise as a wide-bandgap semiconductor with a range of optical, electronic, and mechanical applications. The presence of compensating donors, however, is a major roadblock to achieving p-type conductivity. 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. Given the omnipresence of hydrogen during growth and processing, it is important to determine the structure and stability of hydrogen donors in ZnO.To address these issues, we performed vibrational spectroscopy on bulk, single-crystal ZnO samples annealed in hydrogen (H2) or deuterium (D2) gas. Using infrared (IR) spectroscopy, we observed O-H and O-D stretch modes at 3326.3 cm-1 and 2470.3 cm-1 respectively, at a sample temperature of 10 K. These frequencies indicate that hydrogen forms a bond with a host oxygen atom, consistent with either an antibonding or bond-centered model. In the antibonding configuration, hydrogen attaches to a host oxygen and points away from the Zn-O bond. In the bond-centered configuration, hydrogen sits between the Zn and O. To discriminate between these two models, we measured the shift of the stretch-mode frequency as a function of hydrostatic pressure. By comparing with first-principles calculations, we conclude that the antibonding model is the correct one.Surprisingly, we found that the O-H complex is unstable at room temperature. After a few weeks, the peak intensity decreases substantially. It is possible that the hydrogen forms H2 molecules, which have essentially no IR signature. Electrical measurements show a corresponding decrease in electron concentration, which is consistent with the formation of neutral H2 molecules. The correlation between the electrical and spectroscopic measurements, however, is not perfect. We therefore speculate that there may be a second “hidden” hydrogen donor. One candidate for such a donor is a hydrogen-decorated oxygen vacancy.

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.

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.

Theory of Defects in Wide-Band-Gap Semiconductors

1995 ◽  
Vol 378 ◽  
Author(s):  
Chris G Van de Walle ◽  
Jörg Neugebauer
Keyword(s):  
Band Gap ◽  
First Principles ◽  
State Of The Art ◽  
Wide Band ◽  
First Principles Calculations ◽  
Wide Band Gap ◽  
Native Defects ◽  
In Doping ◽  
Wide Band Gap Semiconductors

AbstractWe discuss the application of state-of-the-art first-principles calculations to the problem of defects, impurities, and doping levels in semiconductors. Since doping problems are of particular relevance in wide-band-gap materials, we focus here on studies of ZnSe and GaN. For ZnSe, we discuss our latest insights in the influence of compensation and dopant solubility on the experimentally observed limitation of the free carrier concentration in p-type ZnSe. For GaN, we focus on the role of native defects in doping or compensation of the material, with particular emphasis on the n-type conductivity of as-grown GaN.

scholarly journals Structural and physical properties of 99 complex bulk chalcogenides crystals using first-principles calculations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sahib Hasan ◽  
Khagendra Baral ◽  
Neng Li ◽  
Wai-Yim Ching
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
First Principles ◽  
Experimental Studies ◽  
First Principles Calculations ◽  
Chalcogenide Semiconductors ◽  
Optical And Mechanical Properties ◽  
Very Large Database ◽  
Unique Composition ◽  
Fundamental Physical

AbstractChalcogenide semiconductors and glasses have many applications in the civil and military fields, especially in relation to their electronic, optical and mechanical properties for energy conversion and in enviormental materials. However, they are much less systemically studied and their fundamental physical properties for a large class chalcogenide semiconductors are rather scattered and incomplete. Here, we present a detailed study using well defined first-principles calculations on the electronic structure, interatomic bonding, optical, and mechanical properties for 99 bulk chalcogenides including thirteen of these crytals which have never been calculated. Due to their unique composition and structures, these 99 bulk chalcogenides are divided into two main groups. The first group contains 54 quaternary crystals with the structure composition (A2BCQ4) (A = Ag, Cu; B = Zn, Cd, Hg, Mg, Sr, Ba; C = Si, Ge, Sn; Q = S, Se, Te), while the second group contains scattered ternary and quaternary chalcogenide crystals with a more diverse composition (AxByCzQn) (A = Ag, Cu, Ba, Cs, Li, Tl, K, Lu, Sr; B = Zn, Cd, Hg, Al, Ga, In, P, As, La, Lu, Pb, Cu, Ag; C = Si, Ge, Sn, As, Sb, Bi, Zr, Hf, Ga, In; Q = S, Se, Te; $$\hbox {x} = 1$$ x = 1 , 2, 3; $$\hbox {y} = 0$$ y = 0 , 1, 2, 5; $$\hbox {z} = 0$$ z = 0 , 1, 2 and $$\hbox {n} = 3$$ n = 3 , 4, 5, 6, 9). Moreover, the total bond order density (TBOD) is used as a single quantum mechanical metric to characterize the internal cohesion of these crystals enabling us to correlate them with the calculated properties, especially their mechanical properties. This work provides a very large database for bulk chalcogenides crucial for the future theoretical and experimental studies, opening opportunities for study the properties and potential application of a wide variety of chalcogenides.

scholarly journals First-principles calculations and experimental studies of XYZ2 thermoelectric compounds: detailed analysis of van der Waals interactions

2018 ◽  
Vol 6 (40) ◽  
pp. 19502-19519 ◽  
Author(s):  
Jan-Hendrik Pöhls ◽  
Zhe Luo ◽  
Umut Aydemir ◽  
Jon-Paul Sun ◽  
Shiqiang Hao ◽  
...  
Keyword(s):  
Detailed Analysis ◽  
First Principles ◽  
Van Der Waals ◽  
Experimental Studies ◽  
Van Der Waals Interactions ◽  
First Principles Calculations ◽  
Prediction Of Properties

van der Waals interactions enhanced the prediction of properties in layered thermoelectrics.

scholarly journals Superb water splitting activity of the electrocatalyst Fe3Co(PO4)4 designed with computation aid

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Siraj Sultan ◽  
Miran Ha ◽  
Dong Yeon Kim ◽  
Jitendra N. Tiwari ◽  
Chang Woo Myung ◽  
...  
Keyword(s):  
Water Splitting ◽  
First Principles ◽  
High Current Density ◽  
Cost Effective ◽  
Great Promise ◽  
First Principles Calculations ◽  
High Turnover ◽  
Faradaic Efficiency ◽  
Reduced Graphene

AbstractFor efficient water splitting, it is essential to develop inexpensive and super-efficient electrocatalysts for the oxygen evolution reaction (OER). Herein, we report a phosphate-based electrocatalyst [Fe3Co(PO4)4@reduced-graphene-oxide(rGO)] showing outstanding OER performance (much higher than state-of-the-art Ir/C catalysts), the design of which was aided by first-principles calculations. This electrocatalyst displays low overpotential (237 mV at high current density 100 mA cm−2 in 1 M KOH), high turnover frequency (TOF: 0.54 s−1), high Faradaic efficiency (98%), and long-term durability. Its remarkable performance is ascribed to the optimal free energy for OER at Fe sites and efficient mass/charge transfer. When a Fe3Co(PO4)4@rGO anodic electrode is integrated with a Pt/C cathodic electrode, the electrolyzer requires only 1.45 V to achieve 10 mA cm−2 for whole water splitting in 1 M KOH (1.39 V in 6 M KOH), which is much smaller than commercial Ir-C//Pt-C electrocatalysts. This cost-effective powerful oxygen production material with carbon-supporting substrates offers great promise for water splitting.

First Principles Modelling of Scroll-to-Nanotube Defect: Screw-Type Dislocation

2006 ◽  
Vol 527-529 ◽  
pp. 1583-1586 ◽  
Author(s):  
I. Suarez-Martinez ◽  
G. Savini ◽  
M.I. Heggie
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Wide Band ◽  
Interlayer Spacing ◽  
Density Functional Theory Study ◽  
Wide Band Gap ◽  
Functional Theory ◽  
Potential Applications ◽  
Wide Band Gap Semiconductors ◽  
Type Dislocation

Carbon nanotubes present interesting potential applications especially in nanoelectronics. Their electrical properties are known to be a function of their chirality. It happens that 1/3 of CNs are metallic and 2/3 are semiconductors. Narrow nanotubes are expected to be wide-band gap semiconductors. Several experimental results have shown that the thickness of a multi-wall nanotube along the axis can change, while the interlayer spacing remains fairly constant. These observations suggest the coexistence in the same tube of a scroll structure and a multi-wall nested tube. We explain this defect as a screw dislocation which by gliding transforms between these two forms. In this paper, we present a density functional theory study of the structure and energetics of screw dislocations in AA and ABC graphite, and we discuss their role in the scroll-to-nanotube transformation in multi-wall nanotubes.

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