Sulfur isotope effects on the excitonic spectra of CdS

Meyer, Thomas Alexander; Thewalt, M. L. W.; Cardona, M.; Lauck, R.

doi:10.1103/physrevb.69.115214

Cited by 54 publications

(91 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The need for two oscillators becomes particularly acute for binary compounds in which cation and anion have very different masses (GaN [50], ZnO [63], CdS [65], CuI [64]). In these cases the acoustic and the optical phonons have rather different average frequencies and, in view of their different coupling to electronic states, it is not possible to replace them by a single Einstein oscillator in order to describe the temperature as well as the isotopic mass dependence of energy gaps.…”

Section: Gallium Nitride Zinc Oxide Cadmium Sulfidementioning

confidence: 99%

Electron–phonon interaction in tetrahedral semiconductors

Cardona

2005

Solid State Communications

163

141

View full text Add to dashboard Cite

Considerable progress has been made in recent years in the field of ab initio calculations of electronic band structures of semiconductors and insulators. The oneelectron states (and the concomitant two-particle excitations) have been obtained without adjustable parameters, with a high degree of reliability. Also, more recently, the electron-hole excitation frequencies responsible for optical spectra have been calculated. These calculations, however, are performed with the constituent atoms fixed in their crystallographic positions and thus neglect the effects of the lattice vibrations (i.e. electron-phonon interaction) which can be rather large, even larger than the error bars assumed for ab initio calculations.Effects of electron-phonon interactions on the band structure can be experimentally investigated in detail by measuring the temperature dependence of energy gaps or critical points (van Hove singularities) of the optical excitation spectra. These studies have been complemented in recent years by observing the dependence of such spectra on isotopic mass whenever different stable isotopes of a given atom are available at affordable prices. In crystals composed of different atoms, the effect of the vibration of each separate atom can thus be investigated by isotopic substitution. Because of the zero-point vibrations, such effects are present even at zero temperature (T = 0).In this paper we discuss state-of-the-art calculations of the dielectric function spectra and compare them with experimental results, with emphasis on the differences introduced by the electron-phonon interaction. The temperature dependence of various optical parameters will be described by means of one or two (in a few cases three) Einstein oscillators, except at the lowest temperatures where the T 4 law (contrary to the Varshni T 2 result) will be shown to apply. Increasing an isotopic mass increases the energy gaps, except in the case of monovalent Cu (e.g., CuCl) and possibly Ag (e.g., AgGaS 2 ). It will be shown that the gaps of tetrahedral materials containing an element of the first row of the periodic table (C,N,O) are strongly affected by the electron-phonon interaction. It will be conjectured that this effect is related to the superconductivity recently observed in heavily boron-doped carbon.

show abstract

Section: Gallium Nitride Zinc Oxide Cadmium Sulfidementioning

confidence: 99%

Electron–phonon interaction in tetrahedral semiconductors

Cardona

2005

Solid State Communications

163

141

View full text Add to dashboard Cite

show abstract

“…Such reconstructions were suggested to be important under high temperature growth. [52] As for the reconstructions with H, numerous possible H covered reconstructions should be considered. However, the lowest energy configurations must be those surfaces that satisfy ECR [52,56].…”

Section: Methodsmentioning

confidence: 99%

“…[52] As for the reconstructions with H, numerous possible H covered reconstructions should be considered. However, the lowest energy configurations must be those surfaces that satisfy ECR [52,56]. It demonstrated that the vibrational entropy of the surface plays a decisive role in the competition among various phases to achieve thermodynamic stability [53].…”

Section: Methodsmentioning

confidence: 99%

“…During the standard OMVPE growth processes, hydrogen is a common unavoidable impurity [48,49], often decomposed from precursors or carrier gases [50]. As a result, hydrogen-involved surface reconstructions have also been reported on the polar surfaces of ZnO [51][52][53][54][55] and GaN [56,57] both in experiments and theories. Such surface reconstructions are usually stable because H may help the surface to satisfy electron-counting-rule (ECR) [58].…”

Section: Introductionmentioning

confidence: 99%

“…It's essential to perform a calculation of the vibrational entropy of H, which is the major component of the chemical potential of H during high temperature growth [52][53][54][55][56][62][63][64][65][66]. In addition to such theoretical calculation, applying the experimental Gibbs free energy of H2 is also a possible alternative method to obtain the quantitative relations of H chemical potential, temperature (T) and pressure (p).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Hydrogen-surfactant-assisted coherent growth of GaN on ZnO substrate

Zhang

Tse

et al. 2018

Phys. Rev. Materials

View full text Add to dashboard Cite

Heterostructures of wurtzite based devices have attracted great research interests since the tremendous success of GaN in light emitting diodes (LED) industry. Among the possible heterostructure material candidates, high quality GaN thin films on inexpensive and lattice matched ZnO substrate are both commercially and technologically desirable. However, the energy of ZnO polar surfaces is much lower than that of GaN polar surfaces. Therefore, the intrinsic wetting condition forbids such heterostructures.As a result, poor crystal quality and 3D growth mode were obtained. To dramatically change the growth mode of the heterostructure, we propose to use hydrogen as a surfactant, confirmed by our first principles calculations. Stable H involved surface configurations and interfaces are investigated, with the help of newly developed algorithms. By applying the experimental Gibbs free energy of H2, we also predict the temperature and chemical potential of H, which is critical in experimental realizations of our strategy. This novel approach will for the first time make the growth of high quality GaN thin films on ZnO substrates possible. We believe that our new strategy may reduce the manufactory cost and improve the crystal quality and the efficiency of GaN based devices.

show abstract

Zinc Oxide Nanoparticles with Defects

Ischenko

Polarz

Grote

et al. 2005

Adv Funct Materials

536

360

View full text Add to dashboard Cite

Zinc oxide in the form of nanoscale materials can be regarded as one of the most important semiconductor oxides at present. However, the question of how chemical defects influence the properties of nanoscale zinc oxide materials has seldom been addressed. In this paper, we report on the introduction of defects into nanoscale ZnO, their comprehensive analysis using a combination of techniques (powder X‐ray diffraction (PXRD), X‐ray absorption spectroscopy/extended X‐ray absorption fine structure (XAS/EXAFS), electron paramagnetic resonance (EPR), magic‐angle spinning nuclear magnetic resonance (MAS‐NMR), Fourier‐transform infrared (FTIR), UV‐vis, and photoluminescence (PL) spectroscopies coupled with ab‐initio calculations), and the investigation of correlations between the different types of defects. It is seen that defect‐rich zinc oxide can be obtained under kinetically controlled conditions of ZnO formation. This is realized by the thermolysis of molecular, organometallic precursors in which ZnO is pre‐organized on a molecular scale. It is seen that these precursors form ZnO at low temperatures far from thermodynamic equilibrium. The resulting nanocrystalline ZnO is rich in defects. Depending on conditions, ZnO of high microstructural strain, high content of oxygen vacancies, and particular content of heteroatom impurities can be obtained. It is shown how the mentioned defects influence the electronic properties of the semiconductor nanoparticles.

show abstract

Sulfur isotope effects on the excitonic spectra of CdS

Cited by 54 publications

References 17 publications

Electron–phonon interaction in tetrahedral semiconductors

Electron–phonon interaction in tetrahedral semiconductors

Hydrogen-surfactant-assisted coherent growth of GaN on ZnO substrate

Zinc Oxide Nanoparticles with Defects

Contact Info

Product

Resources

About