Chapter 6 Absorption near the Fundamental Edge

Johnson, E. J.

doi:10.1016/s0080-8784(08)60318-x

Cited by 103 publications

(26 citation statements)

References 151 publications

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“…For an indirect band gap semiconductor: where hν is the excitation energy, A is a constant, and E g is the band gap [3,43]. Shown in Figure 7 are current-voltage curves for the OMEs in the dark and under illumination.…”

Section: Resultsmentioning

confidence: 99%

Electrodeposition of Nanometer-Sized Ferric Oxide Materials in Colloidal Templates for Conversion of Light to Chemical Energy

Gardner

Kim

Searson

et al. 2011

Journal of Nanomaterials

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Colloidal crystal templates were prepared by gravitational sedimentation of 0.5 micron polystyrene particles onto fluorine-doped tin oxide (FTO) electrodes. Scanning electron microscopy (SEM) shows that the particles were close packed and examination of successive layers indicated a predominantly face-centered-cubic (fcc) crystal structure where the direction normal to the substrate surface corresponds to the (111) direction. Oxidation of aqueous ferrous solutions resulted in the electrodeposition of ferric oxide into the templates. Removal of the colloidal templates yielded ordered macroporous electrodes (OMEs) that were the inverse structure of the colloidal templates. Current integration during electrodeposition and cross-sectional SEM images revealed that the OMEs were about 2 μm thick. Comparative X-ray diffraction and infrared studies of the OMEs did not match a known phase of ferric oxide but suggested a mixture of goethite and hematite. The spectroscopic properties of the OMEs were insensitive to heat treatments at 300• C. The OMEs were utilized for photoassisted electrochemical oxidation. A sustained photocurrent was observed from visible light in aqueous photoelectrochemical cells. Analysis of photocurrent action spectra revealed an indirect band gap of 1.85 eV. Addition of formate to the aqueous electrolytes resulted in an approximate doubling of the photocurrent.

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Section: Resultsmentioning

confidence: 99%

Electrodeposition of Nanometer-Sized Ferric Oxide Materials in Colloidal Templates for Conversion of Light to Chemical Energy

Gardner

Kim

Searson

et al. 2011

Journal of Nanomaterials

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“…The intersection of the tangent to this curve with the x-axis gives the value of the optical gap energy E g in accordance with the following relation [5]:…”

Section: Optical Propertiesmentioning

confidence: 86%

Structural and Optoelectronic Properties of In-Zn-S sprayed Layers

et al. 2008

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In this work, In-Zn-S thin layers were prepared using the spray pyrolysis technique on glass substrates at 320• C. ] one was taken constant equal to 2. The atomic composition was carried out with the atomic absorption. The structural study of all layers via X-ray diffraction and atomic force microscopy shows that the layer, obtained using x = 0 is formed by binary material In2S3 with a principal orientation along (400). When the composition increases the same study depicts the presence of other materials such as ZnO, ZnS, and ZnIn2S4. On the contrary, for x = 0.4, the film is mainly formed by the ternary compound ZnIn2S4 which crystallizes in cubic phase. Moreover, the optical analysis via the transmittance, reflectance as well as the photocurrent reveals that the band gap energy Eg increases slightly as a function of the x composition (Eg varies from 2.6 to 2.9 eV).

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“…5. The analysis of α shows that for hv ≤1.15 eV the rise of α is due to an allowed direct transition described b y [17] witl the gap energy Eg being equal to 1.03 ± 0.01 eV, (see Fig. 6).…”

Section: Resultsmentioning

confidence: 93%

“…This can be explained only by the existence of an additional absorption transition. An analysis of the additional absorption coefficient α' = α -αd showed that this additional absorption may be due to either: i) a forbidden direct transition characterized by [17] or ii) an indirect transition described by [17] Following these two assumptions, tle dependence of (α'hv) 2 / 3 and (α'hv)1/ 2 on hv is partially linear (Fig. 7), the corresponding gap energies were found to be Εgf = (1.03 ± 0.03) and Egi = 0.85 eV, respectively.…”

Section: Resultsmentioning

confidence: 99%

The Optical Properties of CuInSe₂Thin Films

Fouad

Youssef

1992

Acta Phys. Pol. A

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The optical constants of vacuum deposited CuInSe2 thin films of different thicknesses (60-135 nm) were determined in the photon energy from 1.03 to 3.1 eV. It was found that both the refractive index n and the absorption index k are independent of the frlm thickness. The analysis of the experimental points of the refractive index revealed the existence of normal dispersion and fits Sellmeier dispersion formula for single oscillator model. Using the previous model the optical dielectric constant as well as the oscillator energy and dispersion parameter have been calculated. CuInSe 2 is found to be a direct gap semiconductor with a gap energy of 1.03 eV. At energies well above the absorption edge, the absorption behaviour can be explained by the existence of a forbidden direct transition with the same direct energy gap and an indirect one with energy gap of 0.85 eV.

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Chapter 6 Absorption near the Fundamental Edge

Cited by 103 publications

References 151 publications

Electrodeposition of Nanometer-Sized Ferric Oxide Materials in Colloidal Templates for Conversion of Light to Chemical Energy

Electrodeposition of Nanometer-Sized Ferric Oxide Materials in Colloidal Templates for Conversion of Light to Chemical Energy

Structural and Optoelectronic Properties of In-Zn-S sprayed Layers

The Optical Properties of CuInSe₂Thin Films

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Chapter 6 Absorption near the Fundamental Edge

Cited by 103 publications

References 151 publications

Electrodeposition of Nanometer-Sized Ferric Oxide Materials in Colloidal Templates for Conversion of Light to Chemical Energy

Electrodeposition of Nanometer-Sized Ferric Oxide Materials in Colloidal Templates for Conversion of Light to Chemical Energy

Structural and Optoelectronic Properties of In-Zn-S sprayed Layers

The Optical Properties of CuInSe2Thin Films

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The Optical Properties of CuInSe₂Thin Films