Spectroscopic Ellipsometry Analysis of InGaN/GaN and AlGaN/GaN Heterostructures Using a Parametric Dielectric Function Model

1999 ◽  
Vol 595 ◽  
Author(s):  
J. Wagner ◽  
A. Ramakrishnan ◽  
H. Obloh ◽  
M. Kunzer ◽  
K. Köhler ◽  
...  
Keyword(s):  
Band Gap ◽  
Dielectric Function ◽  
Spectroscopic Ellipsometry ◽  
Composition Dependence ◽  
Band Gap Energy ◽  
Function Model ◽  
Gap Energy ◽  
The Individual ◽  
Gap Data

AbstractSpectroscopic ellipsometry (SE) has been used for the characterization of AlGaN/GaN and InGaN/GaN heterostructures. The resulting pseudodielectric function spectra were analyzed using a multilayer approach, describing the dielectric functions of the individual layers by a parametric oscillator model. From this analysis, the dielectric function spectra of GaN, AlxGa1−xN (x≤0.16), and In0.13Ga0.87N were deduced. Further, the dependence of the AlxGa1−xN band gap energy on the Al mole fraction was derived and compared with photoluminescence data recorded on the same material. The SE band gap data are compatible with a bowing parameter close to 1 eV for the composition dependence of the AlxGa1−xN gap energy. Finally, the parametric dielectric functions have been used to model the pseudodielectric function spectrum of a complete GaN/AlGaN/InGaN LED structure.

scholarly journals Spectroscopic Ellipsometry Analysis of InGaN/GaN and AlGaN/GaN Heterostructures Using a Parametric Dielectric Function Model

2000 ◽  
Vol 5 (S1) ◽  
pp. 775-781
Author(s):  
J. Wagner ◽  
A. Ramakrishnan ◽  
H. Obloh ◽  
M. Kunzer ◽  
K. Köhler ◽  
...  
Keyword(s):  
Band Gap ◽  
Dielectric Function ◽  
Spectroscopic Ellipsometry ◽  
Composition Dependence ◽  
Band Gap Energy ◽  
Function Model ◽  
Gap Energy ◽  
The Individual ◽  
Gap Data

Spectroscopic ellipsometry (SE) has been used for the characterization of AlGaN/GaN and InGaN/GaN heterostructures. The resulting pseudodielectric function spectra were analyzed using a multilayer approach, describing the dielectric functions of the individual layers by a parametric oscillator model. From this analysis, the dielectric function spectra of GaN, AlxGa1−xN (x≤0.16), and In0.13Ga0.87N were deduced. Further, the dependence of the AlxGa1−xN band gap energy on the Al mole fraction was derived and compared with photoluminescence data recorded on the same material. The SE band gap data are compatible with a bowing parameter close to 1 eV for the composition dependence of the AlxGa1−xN gap energy. Finally, the parametric dielectric functions have been used to model the pseudodielectric function spectrum of a complete GaN/AlGaN/InGaN LED structure.

Synthesis and characterization of a mixture of CoFe2O4 and MgFe2O4 from layered double hydroxides: Band gap energy and magnetic responses

2014 ◽  
Vol 369 ◽  
pp. 249-259 ◽  
Author(s):  
Ulises A. Agú ◽  
Marcos I. Oliva ◽  
Sergio G. Marchetti ◽  
Angélica C. Heredia ◽  
Sandra G. Casuscelli ◽  
...  
Keyword(s):  
Band Gap ◽  
Layered Double Hydroxides ◽  
Band Gap Energy ◽  
Synthesis And Characterization ◽  
Gap Energy ◽  
Double Hydroxides

scholarly journals Ternary Nanocomposite of ZnFe2O4/α-Fe2O3/ZnO; Synthesis via Coprecipitation Method and Physical Properties Characterization

2021 ◽  
Author(s):  
Somayeh Shams ◽  
Zahra Sheibanizadeh ◽  
Zahra Khalaj
Keyword(s):  
Physical Properties ◽  
Band Gap ◽  
Transition Metal Oxides ◽  
Band Gap Energy ◽  
Coprecipitation Method ◽  
Good Efficiency ◽  
Gap Energy ◽  
Visible Wavelengths ◽  
The Individual ◽  
Post Synthesis

Abstract ZnFe 2 O 4 /α-Fe 2 O 3 /ZnO ternary transition metal oxides nanocomposite powder was successfully synthesized by facile coprecipitation method directly from metalorganic precursors within 4 hours processing time considerably shorter than other reported methods. To study post-synthesis thermal treatment effects on physical properties calcination process was applied at 500 °C, 600 °C and 700 °C individually in furnace for one hour. The structure, phase formation, morphology and optical features of the samples were characterized by means of powder X-ray diffraction, scanning electron microscopy and UV-Visible spectroscopy. The results show formation of pure and homogeneous composites comprised of nanoparticles with good crystallization in narrow range of crystallite size between 25 nm-39 nm. The particle sizes were also estimated to be in the range of 48 nm - 93 nm. The optical property was studied by recording the absorbance spectrum in the range of 200 nm - 700 nm. The absorption pattern illustrated that the product can be driven by both UV and visible wavelengths with a good efficiency which is more desirable for intended applications like photocatalytic activities compare to the individual components. By using Tauc's method the allowed direct band gap energy and indirect band gap energy of the prepared nanocomposite was estimated to be around 2.28 eV and 2.75 eV, respectively.

Optical and Electronic Analysis of Pure and Fe-Doped ZnO Thin Films Using Spectroscopic Ellipsometry and Kramers–Kronig Method

2019 ◽  
Vol 18 (01) ◽  
pp. 1850013 ◽  
Author(s):  
Maryam Motallebi Aghgonbad ◽  
Hassan Sedghi
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Spectroscopic Ellipsometry ◽  
Optical Band Gap ◽  
Band Gap Energy ◽  
Zno Thin Films ◽  
Fe Doping ◽  
Gap Energy ◽  
Optical And Electronic Properties ◽  
Doped Zno

In the present work, pure and Fe-doped ZnO thin films were deposited on glass substrates by sol–gel method. Zinc acetate and iron nitrate were used as the starting material and dopant source, respectively. The concentration of Fe doping was 6[Formula: see text]at.% and 8[Formula: see text]at.%. The optical and electronic properties of pure and Fe-doped ZnO thin films such as refraction index, extinction coefficient, dielectric function and optical band gap energy of the layers were obtained by spectroscopic ellipsometry method in the wavelength range of 300–900[Formula: see text]nm. The incidence angle of the layers kept 70[Formula: see text]. Also data obtained by Kramers–Kronig relations were used for comparison. The influence of Fe-doping concentration on the optical and electronic properties of thin films was studied. The transmittance data of ZnO thin films showed that 6[Formula: see text]at.% Fe-doped ZnO thin film has the highest transmittance value. Dielectric function of pure ZnO films was found to be higher compared with Fe-doped ones. Also it can be deduced from the results that Fe doping influences the optical band gap energy of thin films.

Isotope composition dependence of the band-gap energy in diamond

2013 ◽  
Vol 88 (20) ◽  
Author(s):  
H. Watanabe ◽  
T. Koretsune ◽  
S. Nakashima ◽  
S. Saito ◽  
S. Shikata
Keyword(s):  
Band Gap ◽  
Composition Dependence ◽  
Isotope Composition ◽  
Band Gap Energy ◽  
Gap Energy

Composition dependence of the band gap energy for the dilute nitride and As-rich GaNxSbyAs1−x−y (0≤x≤0.05, 0≤y≤0.3)

2016 ◽  
Vol 485 ◽  
pp. 35-38 ◽  
Author(s):  
Chuan-Zhen Zhao ◽  
Heng-Fei Guo ◽  
Tong Wei ◽  
Sha-Sha Wang ◽  
Ke-Qing Lu
Keyword(s):  
Band Gap ◽  
Composition Dependence ◽  
Band Gap Energy ◽  
Dilute Nitride ◽  
Gap Energy

scholarly journals Composition Dependence of the Band Gap Energy of InxGa1−xN Layers on GaN (x≤0.15) Grown by Metal-Organic Chemical Vapor Deposition

1999 ◽  
Vol 4 (S1) ◽  
pp. 106-111 ◽  
Author(s):  
J. Wagner ◽  
A. Ramakrishnan ◽  
D. Behr ◽  
M. Maier ◽  
N. Herres ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Band Gap ◽  
Vapor Deposition ◽  
Composition Dependence ◽  
Chemical Vapor ◽  
Band Gap Energy ◽  
Organic Chemical ◽  
Gap Energy ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

We report on the composition dependence of the band gap energy of strained hexagonal InxGa1−xN layers on GaN with x≤0.15, grown by metal-organic chemical vapor deposition on sapphire substrates. The composition of the (InGa)N was determined by secondary ion mass spectroscopy. High-resolution X-ray diffraction measurements confirmed that the (InGa)N layers with typical thicknesses of 30 nm are pseudomorphically strained to the in-plane lattice parameter of the underlying GaN. Room-temperature photoreflection spectroscopy and spectroscopic ellipsometry were used to determine the (InGa)N band gap energy. The composition dependence of the band gap energy of the strained (InGa)N layers was found to be given by EG(x)=3.43−3.28 × (eV) for x≤0.15. When correcting for the strain induced shift of the fundamental energy gap, a bowing parameter of 3.2 eV was obtained for the composition dependence of the gap energy of unstrained (InGa)N.

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