Moments of phonon density of states spectra and characteristic phonon temperatures of wide band gap materials

2006 ◽  
Vol 243 (12) ◽  
pp. 2719-2727 ◽  
Author(s):  
Roland Pässler
Keyword(s):  
Band Gap ◽  
Density Of States ◽  
Wide Band ◽  
Phonon Density ◽  
Phonon Density Of States ◽  
Wide Band Gap

Structural, Phonon and Thermodynamic Properties of the Rocksalt Structure LiF from First Principles

2016 ◽  
Vol 850 ◽  
pp. 348-353 ◽  
Author(s):  
Hai Jun Hou ◽  
Hao Guan ◽  
Shun Ru Zhang ◽  
Lin Hua Xie ◽  
Lei Wang
Keyword(s):  
Thermodynamic Properties ◽  
Density Of States ◽  
Phonon Dispersion ◽  
Local Density ◽  
Wide Band ◽  
Present Calculation ◽  
Phonon Density ◽  
Phonon Density Of States ◽  
Rocksalt Structure ◽  
Theoretical Results

The structural, electronic, phonon and thermodynamic properties of rocksalt (RS) structure LiF are studied using a plane-wave pseudopotential method within the local density approximation (LDA). The values of lattice constants, elastic constants, and bulk modulus and its pressure derivatives are in well agreement with the available experimental data and other theoretical results. The LiF crystal exhibits a wide band gap of about 8.727 eV. The linear response method is applied to determine the phonon dispersion, phonon density of states and Born effective charge. The phonon frequencies at the Γ, X, L points are analyzed using group theory. We also calculate the thermodynamic functions such as free energy, enthalpy, entropy, specific heat using the phonon density of states. We compare the present calculation results satisfactorily to experimental and previous theoretical results.

Joint Density of States of Wide-Band-Gap Materials by Electron Energy Loss Spectroscopy

1998 ◽  
Vol 12 (13) ◽  
pp. 541-554 ◽  
Author(s):  
X. D. Fan ◽  
J. L. Peng ◽  
L. A. Bursill
Keyword(s):  
Energy Loss ◽  
Band Gap ◽  
Electron Energy ◽  
Dielectric Function ◽  
Density Of States ◽  
Electron Energy Loss Spectroscopy ◽  
Wide Band ◽  
Joint Density ◽  
Wide Band Gap ◽  
Electron Energy Loss

Kramers–Kronig analysis for parallel electron energy loss spectroscopy (PEELS) data is developed as a software package. When used with a JEOL 4000EX high-resolution transmission electron microscope (HRTEM) operating at 100 keV this allows us to obtain the dielectric function of relatively wide band gap materials with an energy resolution of approx. 1.4 eV. The imaginary part of the dielectric function allows the magnitude of the band gap to be determined as well as the joint-density-of-states function. Routines for obtaining three variations of the joint-density of states function, which may be used to predict the optical and dielectric response for angle-resolved or angle-integration scattering geometries are also described. Applications are presented for diamond, aluminum nitride (AlN), quartz ( SiO 2) and sapphire ( Al 2 O 3). The results are compared with values of the band gap and density of states results for these materials obtained with other techniques.

NEW RESULTS ON OPTICAL ABSORPTION IN AMORPHOUS CADMIUM OXIDE FOR THE VISIBLE RANGE: A THEORETICAL APPROACH

2004 ◽  
Vol 18 (24) ◽  
pp. 1255-1259 ◽  
Author(s):  
M. A. GRADO-CAFFARO ◽  
M. GRADO-CAFFARO
Keyword(s):  
Experimental Data ◽  
Optical Absorption ◽  
Band Gap ◽  
Density Of States ◽  
Theoretical Approach ◽  
Cadmium Oxide ◽  
Visible Region ◽  
Visible Range ◽  
Phonon Density ◽  
Phonon Density Of States

Optical absorption of amorphous cadmium oxide in the visible region is investigated by considering the band-gap shift experienced by this material. At the same time, influence of oxygen partial pressure is studied so that new results related to absorption in the visible margin are obtained; these results agree well with experimental data. In addition, phonon density of states and its shift due to the band-gap shift are evaluated.

TEM and cathodoluminescence of precipitates in II-VI semiconductors

1988 ◽  
Vol 46 ◽  
pp. 488-489
Author(s):  
Joanna L. Batstone
Keyword(s):  
Crystal Growth ◽  
Band Gap ◽  
Local Strain ◽  
Wide Band ◽  
Optoelectronic Device ◽  
Wide Band Gap ◽  
Bulk Crystal Growth ◽  
Transmission Electron ◽  
Device Applications ◽  
Stoichiometry Control

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-x Te are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.

The solids phonon density of states reconstruction from the heat-type experiments: the computation resources

1998 ◽  
Vol 3 (0) ◽  
pp. 135-138
Author(s):  
В. М. Різак ◽  
І. М. Різак ◽  
І. П. Коссей ◽  
В. В. Маслюк
Keyword(s):  
Density Of States ◽  
Phonon Density ◽  
Phonon Density Of States

Wide Band-Gap Kesterite Thin Films for Photovoltaic Applications

2018 ◽  
Author(s):  
Raquel Caballero ◽  
Leonor de la Cueva ◽  
Andrea Ruiz-Perona ◽  
Yudenia Sánchez ◽  
Markus Neuschitzer ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Wide Band ◽  
Wide Band Gap ◽  
Photovoltaic Applications

Preparation and Characterization of Polyvinylidene Fluoride/ZrO2-TiO2 Optical Film with Wide Band Gap and High Refractive Index

2013 ◽  
Vol 28 (6) ◽  
pp. 671-676 ◽  
Author(s):  
Yu-Qing ZHANG ◽  
Li-Li ZHAO ◽  
Shi-Long XU ◽  
Chao ZHANG ◽  
Xiao-Ying CHEN ◽  
...  
Keyword(s):  
Refractive Index ◽  
Band Gap ◽  
Polyvinylidene Fluoride ◽  
Wide Band ◽  
High Refractive Index ◽  
Wide Band Gap ◽  
Optical Film
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