共查询到20条相似文献,搜索用时 31 毫秒
1.
H. Neumann P. A. Jones H. Sobotta W. Hrig R. D. Tomlinson M. V. Yakushev 《Crystal Research and Technology》1996,31(1):63-74
Optical absorption spectra in the photon energy range from 0.03 to 1.1 eV and photoreflectance spectra in the range of the fundamental edge are measured on p-type CuInSe2 single crystals. Besides a dominant contribution to the absorption coefficient due to intervalence band transitions below about 0.75 eV the spectra revealed five additional structures that can be ascribed to defect induced optical transitions with characteristic energies between 0.48 and 0.72 eV. Based on a comparison of the near-edge optical absorption and photoreflectance spectra a shallow defect (donor or acceptor) with an ionisation energy of about 46 meV was identified. 相似文献
2.
From the measured absorption and reflection spectra, we have determined the optical properties of a well-characterized (with respect to impurities and homogeneity) high-purity 21.3 wt% Na2O?5.2 wt% CaO?73.5 wt% SiO2 glass over the energy range 0.006–22 eV. The origins of the absorption spectra are discussed. 相似文献
3.
W. Hrig H. Neumann V. Savelev J. Lagzdonis B. Schumann G. Kühn 《Crystal Research and Technology》1989,24(8):823-827
Optical absorption spectra of flash-evaporated polycrystalline thin films of CuInTe2 are measured in the photon energy range from 0.5 to 3.0 eV. A gap energy in the range from 0.96 to 0.99 eV and a spin-orbit splitting of the valence band of 0.61 ± 0.03 eV are derived from the spectra. It is found that the spectra are considerably influenced by grain boundary effects. 相似文献
4.
V. Riede H. Neumann V. Krmer M. Kittel H. Sobotta 《Crystal Research and Technology》1991,26(5):639-643
Transmittance and reflectance spectra of CdIn2Te4 are measured in the wavenumber range from 200 to 4000 cm–1. In the range from 200 to 400 cm–1 the spectra are governed by two-phonon combination mode absorptions. In the wavenumber range above 400 cm–1 absorption coefficients below 1 cm–1 and a constant reflectivity of about 0.21 are found. 相似文献
5.
H. Sobotta H. Neumann S. Mitaray V. Riede G. Kühn 《Crystal Research and Technology》1987,22(9):1173-1178
Infrared absorption spectra of Cu1−xLixInSe2 thin films are measured at room temperature in the wavenumber range from 100 to 600 cm−1. The spectra exhibit two absorption bands in the wavenumber ranges 200–210 cm−1 and 330–355 cm−1 which are ascribed to vibrational modes due to In Se and Li Se vibrations, respectively. The influence of the phase transition from the chalcopyrite structure to the β-NaFeO2 structure in the composition range x = 0.5–0.6 on the vibrational characteristics is established and discussed. 相似文献
6.
N. Tigau 《Crystal Research and Technology》2008,43(9):964-969
Thin films of antimony trisulfide (Sb2S3) were prepared by thermal evaporation under vacuum (p=5×10–5 torr) on glass substrates maintained at various temperatures between 293 K and 523 K. Their microstructural properties have obtained by transmission electron microscopy (TEM). The electron diffraction analysis showed the occurrence of amorphous to polycrystalline transition in the films deposited at higher temperature of substrates (523 K). The polycrystalline thin films were found to have an orthorhombic structure. The interplanar distances and unit‐cell parameters were determined by high‐resolution transmission electron microscopy (HRTEM) and compared with the standard values for Sb2S3. The surface morphology of Sb2S3 thin films was investigated by scanning electron microscopy (SEM). The optical transmission spectra at normal incidence of Sb2S3 thin films have been measured in the spectral range of 400–1400 nm. The analysis of the absorption spectra revealed indirect energy gaps, characterizing of amorphous films, while the polycrystalline films exhibited direct energy gap. From the photon energy dependence of absorption coefficient, the optical band gap energy, Eg, were calculated for each thin films. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
The effect of γ-irradiation in the dose range of 5 kGy up to 25 kGy on the optical absorption spectra of 50PbO–50P2O5 glasses is reported. The spectral absorption of these glasses before and after γ-irradiation was measured in the spectral range of 300–900 nm at room temperature. The radiation induced absorption in this spectral range shown to consist of two bands centered approximately at 545 nm and 730 nm. The fundamental absorption edge shifts generally to lower energies with increasing γ-irradiation dose up to 25 kGy in this glass sample. The intensity of the induced absorption bands increases linearly with increasing γ-irradiation dose. The higher energy band (HEB) may be due to a hole in a singly bonded non-bridging oxygen distant from a modifier cation, while the lower energy band (LEB) is also due to a hole in similar oxygen which is interacting with a neighboring cation. 相似文献
8.
A. Zegadi H. Neumann M. A. Slifkin R. D. Tomlinson 《Crystal Research and Technology》1993,28(1):83-88
Optical absorption spectra of n-type CuInSe2 single crystals were evaluated by means of photoacoustic spectroscopy in the photon energy range from 0.94 to 1.02 eV. At photon energies below 0.99 eV the spectra exhibit exponential tails that are ascribed to the presence of shallow impurity states. At higher photon energies the absorption coefficients follow the relation for direct allowed optical transitions between parabolic bands. The parameters of this relation are determined and compared with previous measurements. 相似文献
9.
Photoluminescence spectra of Tl4GaIn3S8 layered crystals grown by Bridgman method have been studied in the wavelength region of 500–780 nm and in the temperature range of 26–130 K with extrinsic excitation source (λexc = 532 nm), and at T = 26 K with intrinsic excitation source (λexc = 406 nm). Three emission bands A, B and C centered at 514 nm (2.41 eV), 588 nm (2.11 eV) and 686 nm (1.81 eV), respectively, were observed for extrinsic excitation process. Variations in emission spectra have been studied as a function of excitation laser intensity in the 0.9‐183.0 mW cm–2 range for extrinsic excitation at T = 26 and 50 K. Radiative transitions from the donor levels located at 0.03 and 0.01 eV below the bottom of the conduction band to the acceptor levels located at 0.81 and 0.19 eV above the top of the valence band were proposed to be responsible for the observed A‐ and C‐bands. The anomalous temperature dependence of the B‐band peak energy was explained by configurational coordinate model. From X‐ray powder diffraction and energy dispersive spectroscopic analysis, the monoclinic unit cell parameters and compositional parameters of Tl4GaIn3S8 crystals were determined, respectively. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
10.
A series of glass specimens was prepared from mixtures of SiO2, TiO2 and Na2O, and their optical absorption coefficients measured as functions of photon energy in the range 2.1–3.3 eV. From the results, values of the optical energy gap are calculated and found to be dependent on the glass compositions. The results are analysed in terms of a mechanism of optical absorption arising from forbidden indirect transitions. 相似文献
11.
The crystals of the complexes Er(Gly)3Cl3. 3 H2O and Er(Ala)3Cl3. 3 H2O were synthesized and the photoacoustic (PA) spectra in the 300–800 nm region are reported. Their PA and absorption spectra are interpreted. The PA relative intensities represented by intensity branching vectors and the perturbation of ligands on the energy levels of Er3+ ion are discussed. The fluorescene properties of Er(Gly)3Cl3. 3 H2O and the relaxation process models were also studied based on the PA and absorption spectra. 相似文献
12.
The optical unpolarized absorption spectra of Hg2Cl2 and Hg2Br2 single crystals were measured in the spectral range 230–400 nm. A sharp exciton peak and other absorption bands of both halides were observed near the fundamental absorption edge. The absorption peaks due to the splitting of the halogen doublet were also observed. Positions of the exciton peaks are characteristic for the Frenkel (localized) type of excitons. Possible interpretations of the other observed bands are discussed. 相似文献
13.
Photoluminescence (PL) spectra of Tl4Ga3InSe8 layered crystals grown by Bridgman method have been studied in the wavelength region of 600‐750 nm and in the temperature range of 17‐68 K. A broad PL band centered at 652 nm (1.90 eV) was observed at T = 17 K. Variations of emission band has been studied as a function of excitation laser intensity in the 0.13 to 55.73 mW cm‐2 range. Radiative transitions from donor level located at 0.19 eV below the bottom of conduction band to shallow acceptor level located at 0.03 eV above the top of the valence band were suggested to be responsible for the observed PL band. From X‐ray powder diffraction and optical absorption study, the parameters of monoclinic unit cell and the energy of indirect band gap were determined, respectively. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
14.
A. Abu El-Fadl 《Crystal Research and Technology》1999,34(8):1047-1054
The effect of temperature on the optical absorption spectra and optical parameters is investigated for pure TGS and TGS doped with Cu2+ ions. Absorption measurements cover the range from room temperature to about 355 K in the energy range 3-5.5 eV. The temperature dependence of the band gap Eg(T) reveals an anomaly at the phase transition temperature for both pure and Cu2+-doped TGS crystals. In the region of the absorption edge the absorption coefficient is found to display Urbach-rule behaviour. The characteristic Urbach parameters are determined and their temperature dependence is investigated. 相似文献
15.
Woong Shin Gyeong Eun Lim Nadhila Sylvianti Mutia Anissa Marsya Devi Saskia Putri Youn Whan Kim 《Molecular Crystals and Liquid Crystals》2016,635(1):40-44
ABSTRACTA series of small-molecules (SMs) based on coplanar perylene unit coupled with diketopyrrolopyrrole chromophoric core exhibit broad absorption in the range of 500–800 nm and low bandgap energise of 1.6–1.7 eV. The power conversion efficiency approximately reach at 0.4% under 1.5 G illumination is achieved for organic solar cells based on a small-molecule bulk heterojunction system consisting of SMs as a donor and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as an acceptor. 相似文献
16.
Liang Li Ya Fan Dejun Wang Guanlin Feng Dapeng Xu 《Crystal Research and Technology》2011,46(5):475-479
The transmittance and absorption spectra of a high‐quality Zn2TiO4 single crystal have been measured along the a‐axes at room‐temperature in the range of 200‐1000 nm. The wavelength dependent refractive index, extinction coefficient, real and imaginary parts of the complex dielectric constant of the Zn2TiO4 crystal have been derived from the measured T and α spectra. By fitting the refractive index spectrum, the Sellmeier dispersion equation of the Zn2TiO4 crystal has been obtained. The validity of Cauchy‐Sellmeier equation has been evaluated in the energy range of 2.90–3.20 eV representing the Urbach tail. Applying the single‐effective oscillator model, the dispersion energy Ed and the oscillator energy E0 have been determined as 18.76 and 5.05 eV, respectively. The obtained dispersion energy Ed takes on ionic crystal value. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
17.
Dimitrina Petrova Marin Gospodinov Peter Sveshtarov 《Crystal Research and Technology》1996,31(5):577-581
Single crystals of Bi12SiO20 (BSO) Zn- and Cd-doped and co-doped with P have been grown by Czochralski technique and optimum conditions for producing optically homogeneous crystals were established. The transmission and reflection spectra have been measured in the range 0.38–0.85 μm and absorption coefficients have been determined. The Zn dopants have been found to bleach the crystals and decrease the transmission shoulder, whereas Cd dopant increases the absorption and makes the shoulder well pronounced. P-doping strongly decreases the transmission shoulder and shifts absorption to shorter wavelengths. The absorption Coefficient of BSO doped with P has been found to decrease with dopant concentration increase up to 3 mol% P and above it increases with P concentration in the whole studied range. Zn + P- and Cd + P-co-doping (P concentration in the crystal less than 3 mol%) decreases strongly the absorption coefficient and shifts the spectra to short wavelengths. 相似文献
18.
《Journal of Non》1986,85(3):382-392
The infrared absorption spectra both of ultrathin plasma SiO2 and of thermal oxide (15–100 nm) treated in RF O2 plasma are investigated in the wave number range from 400 to 4000 cm−1. A conclusion is made that the plasma oxide consists of amorphous and different kinds of crystalline phases. The IR spectra of plasma oxide depend slightly on the discharge parameters. The structure of the as-grown thermal oxide, thinner than 40 nm, is shown to have defects and the presence of crystalline phases is observed too. The IR spectra of these oxides are changed significantly after plasma exposure. The influence of RF O2 plasma on the thermal oxide, thicker than 40 nm, is negligible with respect to structural changes. 相似文献
19.
Bożena Jarząbek Jan Weszka Marian Domański Jan Jurusik Jan Cisowski 《Journal of Non》2008,354(10-11):856-862
Optical transmission and fundamental reflectivity spectra of aromatic polyazomethine thin films, obtained by vacuum evaporation via the polycondensation process have been investigated in the wide spectral range 0.49–6.2 eV. As initial monomers, terephaldehyde (TPA) and one of four different amines, i.e. paraphenylene-diamine (PPDA), 7,2-diamino-fluorene, 1,1′-biphenyl-3,3′,4,4′-tetramine and 3-amino-4-(1-naphthyldiazenyl)phenylamine (fat brown RR) have been used, respectively. Amorphous character of these films was confirmed by the results of X-ray diffraction and AFM investigations. Absorption coefficient of the films has been obtained and the edge of absorption seems to be similar to the absorption edge typical for amorphous semiconductors, what allowed to obtain the Urbach energy and ET parameter. The energy gaps of the films, following the Tauc relation, are found to change from 2.05 to 2.4 eV, depending on the length of conjugated part of the polymer chain. Absorption bands above the absorption edge, observed for different polyazomethine films are connected with their chemical structure and possible electronic transitions. 相似文献
20.
Optical absorption spectra of Cu2+ d–d transition peak in sodium borosilicate glasses and their melts were measured from room temperature to 1100 K. In the case of borate glass free from silicon, increase of the temperature above Tg shifts the peak position to the low energy side and decreases the peak height. Peak width is gradually increased with the increase in temperature. On the other hand, in the case of silicate glass free from boron, peak width is decreased with the increase in temperature from room temperature to liquidus temperature. In addition, peak height is slightly decreased with the temperature increase in this temperature range. Further increase of the temperature makes the peak width large. In borosilicate glasses, temperature dependence of the optical absorption spectra is different both from borate and from silicate, and the temperature dependences of the peak position and of the peak height are very small. Temperature dependence of the peak width depends on the boron/silicon ratio. 相似文献