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1.
Spectroscopic ellipsometry measurements of CuInSe 2 (CIS) and CuIn 1−xGa xSe 2 (CIGS) over a range of Cu compositions reveal that there are important differences in electronic and optical properties between α-phase CIS/CIGS and Cu-poor CIS/CIGS. We find a reduction in the imaginary part of the dielectric function ?2 in the spectral region, 1-3 eV. This reduction can be explained in terms of the Cu-3 d density of states. An increase in band gap is found for Cu-poor CIS and CIGS due to the reduction in repulsive interaction between Cu-3 d and Se-4 p states. We also characterize the dielectric functions of polycrystalline thin-film α-phase CuIn 1−xGa xSe 2 ( x=0.18 and 0.36) to determine their optical properties and compare them with similar compositions of bulk polycrystalline CuIn 1−xGa xSe 2. The experimental results have important implications for understanding the functioning of polycrystalline optoelectronic devices. 相似文献
2.
In this paper the dependence of structural properties of the quaternary CuIn1-xGaxSe2 films with tetragonal structure on the Ga content has been systematically investigated by Raman scattering and x-ray diffraction spectra. The shift of the dominant A1 mode, unlike the lattice constants, does not follow the linear Vegard law with increasing Ga content x, whereas exhibits approximately polynomial change from 174 cm^-1 for CuInSe2 to 185 cm^-1 for CuGaSe2. Such behaviour should be indicative of presence of the asymmetric distribution of Ga and In on a microscopic scale in the films, due to Ga addition. The changes in the tetragonal distortion η lead to a significant variation in the anion displacement parameter U, which should be responsible for the evolution of bond parameters and resultant Raman bands with x. 相似文献
3.
P-type CIGS (CuIn 1-xGa xSe 2) thin films are electro-deposited on a p-type c-Si substrate with a galvanostatic mode to form CIGS(p)/c-Si(p) hetero-junction. The Ga content is varied up to x = 30%. The physical properties of formed CIGS films are characterized by XRD, SEM, EDS and UV–Visible spectroscopy. With x = 30%, we obtain a single chalcopyrite phase of CIGS with a tetragonal crystal structure, a high crystallinity, an orientation toward the (112) direction and a band gap energy of 1.40 eV.AM1.5 J-V performed on the CuI 0.7G 0.3Se 2/c-Si hetero-junction reveals interesting photovoltaic parameters with an efficiency of 3.75%. In addition, using the energy diagram of the hetero-junction calculated with the Anderson model, we show that it could play a dual role when combined to a c-Si cell in a Ag–Al/c-Si(n +)/c-Si(p)/CIGS(p)/Al new architecture. Therefore, in addition to its interesting photovoltaic parameters, this hetero-junction can substitute the BSF. 相似文献
4.
Bond properties of the chalcopyrite and (defect) stannite phases in the Cu–(In,Ga)–Se system are compared in view of the bond overlap population calculated by the molecular orbital calculation of the DV-Xα method. Bond stretching force constant α is estimated for the stannite phases through the bond Ovlp. The Cu–Se and In(Ga)–Se bonds in defect stannite structure are considered to be mechanically weakened by the 2b-site vacancies. We estimate the weakened force constants to be 60–70% of those in the chalcopyrite structure. On the other hand, in In(Ga)-rich stannite, In(Ga) 4d–Se 8i and In(Ga) 2b–Se 8i bonds are estimated to be tighter by 23–25 and 8–9%, respectively, than In(Ga) 4b–Se 8d bond in the chalcopyrite structure. The Γ1 frequencies of the stannite phases are also calculated using the estimated force constants. Characteristic Raman signals peaked at 160–175 cm −1 observed for the Cu(In 1−xGa x) 3Se 5 system are explained by the Cu-rich phase for the Cu–In–Se system, and the phase combination of Cu-rich and Ga 2aV 2b types for the Cu–Ga–Se system from these calculations. 相似文献
5.
Using a reactive co-sputtering from Cu 0.6Ga 0.4 and Cu 0.4In 0.6 alloy targets, we prepared CuIn 1−xGa xSe 2 (CIGS) thin films on Mo/soda-lime glass (SLG) in association with a thermal cracker for elemental atomic Se radicals. The film growth was performed at 500 °C for 90 min. To achieve the composition ratio of CIGS absorber layer, Cu 0.6Ga 0.4 target was set at RF power of 50 W, 60 W, 70 W, and 80 W while keeping at 100 W for Cu 0.4In 0.6 alloy target. Post-annealing was done for all the CIGS films at 550 °C for 30 min. The composition ratio of [Cu]/[In + Ga] and [Ga]/[In + Ga] was increased with RF power but showed no change after post-annealing. X-ray diffraction analysis revealed all the samples has grown dominantly in the [112] crystal orientation. We found the Cu 2−xSe and (InGa) 2−xSe 3 defect phase both at the surface and in the bulk, and developed with post-annealing. From the devices fabricated in the structure of grid/ITO/i-ZnO/CdS/CIGS/Mo/soda-lime glass (SLG), the external quantum efficiency (EQE) was observed to improve in the wavelength, λ ≥ 550 nm in the samples treated with annealing. In the current–voltage ( J–V) measurements, the solar cell showed the best performance of FF = 54.1%, Voc = 0.48 V, Jsc = 33.1 mA/cm 2 and η = 8.5% in the sample with [Cu]/[In + Ga] = 0.84 that improved largely from η = 4.6% for the solar cell with an as-grown CIGS films. 相似文献
6.
The aim of this work was to study the influence of selenization temperature on the morphological and structural properties of CuIn 1−xGa xSe 2 (CIGS) polycrystalline thin films prepared by a two-step method. The compound and metallic precursors were deposited sequentially using GaSe, InSe and Cu sources by thermal evaporation. These identical InSe/Cu/GaSe precursors are then selenized with Se vapor in a vacuum system. All the CIGS films showed chalcopyrite structure and presence of secondary phases observed at low temperatures. High temperature treatment led to better crystalline and an increase in grain size. Solar cell devices are fabricated and J– V measurements performed under AM1.5 global solar spectra conditions at 25 °C are presented. 相似文献
7.
This work reports that the ablation characteristics of thin CuIn 1?x Ga x Se 2 (CIGS) solar cell film differ significantly with elemental composition and laser pulse energy. From in situ shadowgraphs measured during Nd:YAG laser (1,064 nm) irradiation of CIGS films and crater morphologies, it was found that strong surface evaporation is dominant for low Ga concentration films of which band gap is well below the photon energy. As the band gap of CIGS film becomes close to or over the laser photon energy due to increased Ga content, surface absorption diminishes and at low laser energy, laser heating of the film plays an important role. It is demonstrated that for the CIGS films with Ga/(Ga + In) ratio being approximately over 0.2, the laser irradiation leads to solid phase removal of the film due to thermomechanical fracture at low laser energy but to ablative evaporation at elevated energy. 相似文献
8.
0.38Bi(Ga x Sc 1–x )O 3–0.62PbTiO 3 (BGSPT x) ceramics have been prepared by using the conventional mixed oxide method. X‐ray diffraction analysis revealed that BGSPT x has a pure perovskite structure, and the crystal symmetry of BGSPT x changed from rhombohedral to tetragonal with increasing Ga content ( x). The Curie temperature ( TC) of BGSPT x ceramics is in the range of 448–467 °C for different x. The ferroelectric phase transition of BGSPT x was found to be of the first order type according to the Curie–Weiss law. For x = 0.125, BGSPT x ceramics show enhanced piezoelectric properties: piezoelectric constant d33 = 420 pC/N and d31 = –142 pC/N, planar and thickness electromechanical coupling factors kp = 56.27% and kt = 56.00%, respectively. The high‐ TC of BGSPT x coupled with its excellent piezoelectric properties suggests those future high‐temperature applications. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
9.
Device-grade polycrystalline thin-film Cu(In 1−xGa x)Se 2 was treated with (NH 4) 2S at 60°C to determine the resulting microscopic surface composition/morphology. Scanning electron microscopy was used to evaluate the resultant macroscopic surface morphology. Modification of the surface and grain boundary chemistry of the Cu(In 1−xGa x)Se 2 polycrystalline films was investigated with scanning photoemission spectromicroscopy. The submicrometer lateral resolution of this technique allows us to directly characterize not only the surface chemistry of the treated films on the submicron scale, but also to probe the grain boundary chemistry. Chemical maps depicting the distribution of chemical species on the surface and at grain boundaries were obtained by monitoring the S 2p, Se 3d, In 4d/Ga 3d and Cu 3d (valence band) photoelectrons while scanning the sample. Background maps were also acquired of each of the peak energies to separate chemical contrast from topographic contrast. Results show that S has been incorporated at the surface, possibly creating a wider bandgap Cu(In 1−xGa x)(Se 1−yS y) 2 surface layer, and along the grain boundaries. The purpose of this investigation is to find an environmentally safe replacement for the toxic CdS overlayer commonly used for heterojunction devices without sacrificing overall device performance and reliability. 相似文献
10.
A mixture of elemental Ga and Se with the nominal composition Ga 40Se 60 was submitted to the Mechanical alloying technique and their structural, thermal and optical properties were followed by X-ray diffraction, differential thermal analysis, photoacoustic spectroscopy, UV-VIS‐NIR absorbance spectroscopy and Raman spectroscopy techniques. After 10 h of milling the X-ray pattern showed monoclinic Ga 2Se 3 phase nucleation, which is in the nanometric form, and also a minority amorphous phase. The DSC results showed exothermic reactions between 430 and 720 K attributed to amorphous-crystalline phase transition and structural relaxation of Ga 2Se 3 phase. Based on this a small amount of the as-milled sample was annealed at 723 K. Its XRD pattern showed evidences of grain growth, reduction of the interfacial component, as well as, disappearance of the amorphous phase. The annealing process induced thermal diffusivity increasing, while the optical band gap energy and Raman profile remained practically unchanged. 相似文献
11.
Polycrystalline thin films of CuIn 2.95Ga 0.05Se 5 produced by the incorporation of Ga into the ordered vacancy compound CuIn 3Se 5 by a two-stage vacuum evaporation process were structurally, compositionally and optically characterized using X-ray diffraction, energy dispersive analysis of X-rays and optical absorbance measurements. From the X-ray diffraction data of the films, the structural parameters like lattice constants, tetragonal deformation, bond lengths and anion displacement were evaluated and their effect on the optical behavior of films was discussed. The Hopfields quasi-cubic model adapted for chalcopyrites with tetragonal deformation was used to elucidate the crystal field and spin orbital splitting parameters in the uppermost valence band of the compound, using the three energy gaps 1.649, 1.718 and 1.92 eV corresponding to the threefold absorption in the fundamental absorption region of the optical spectra of these films. The percentage contributions of Se p and Cu d orbitals to p-d hybridization in this compound were calculated using linear hybridization of orbitals model and the effects of p-d hybridization on the band gaps were studied. 相似文献
12.
Nanostructured materials have become an attractive alternative to their thin film and bulk counterparts in photovoltaic and photoconductivity research. This is mainly attributed to their superior optical and electrical properties. Light trapping in vertically aligned nanostructures results in high optical absorption and provides enhanced carrier collection by utilizing a fully depleted p–n‐junction between the anode and cathode via an isolated ”capping” construction. The combination of these two features can potentially lead to the development of high efficiency nanostructured devices including solar cells, photodiodes, and photodetectors. Optical absorption proper ties of nanorod arrays of CuIn x Ga 1–xSe 2 (CIGS), a p‐type semiconductor with a wide band gap ranging from 1.0 eV to 1.7 eV, are compared to their thin film counterpart. Utilizing an RF sputtering system, a quaternary target, and glancing angle deposition (GLAD) technique, vertical arrays of CIGS nanorods were fabricated while conventional films were fabricated by normal incidence deposition. Scanning electron microscopy (SEM) images indicated a successful growth of CIGS nanorods. Optical absorption was found to be strongly altered by the presence of the nanorod structures through spectroscopic reflectometry. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
13.
The aim of this work was to study the effect of MoN x film substrates on the structural properties of CuInSe 2 films prepared by selenization of metallic Cu-In alloy precursors. MoN x films were prepared by reactive dc-magnetron sputtering. All the CuInSe 2 films exhibit single phase chalcopyrite structure with (1 1 2) preferred orientation, which can be explained by the reduction of lattice mismatch between CuInSe 2 and MoN x. The bulk composition of selenized CuInSe 2 films are near stoichiometric, but the surface composition analysis suggests Cu deficiency on surface area. Furthermore, ordered defect compound, CuIn 2Se 3.5 is found on the surface of CuInSe 2 films. The results will be helpful for fabricating Cd-free ZnO buffer layer CuInSe 2 and Cu(In 1−xGa x)Se 2 based thin film solar cells. 相似文献
14.
使用等离子体活化硒源对电沉积制备的Cu-In-Ga金属预制层进行了硒化处理时, 发现等离子体功率对Cu(In 1-xGa x)Se 2(CIGS)晶粒的生长有重要影响, 当等离子体功率为75 W时, 制备出单一Cu(In 0.7Ga 0.3)Se 2相的CIGS薄膜. 通过对不同衬底温度的等离子体活化硒源硒化的CIGS 薄膜进行了研究与分析, 并与普通硒化后的薄膜进行对比, 发现高活性硒在低温下会促进Ga-Se二元相的生成, 从而有利于Cu(In 0.7Ga 0.3)Se 2单相的生长. 对等离子体硒化后的CIGS薄膜进行了电池制备, 发现单相CIGS薄膜没有显著提高电池性能. 通过优化工艺, 所制备的CIGS电池效率达到了9.4%.
关键词:
0.7Ga 0.3)Se 2')" href="#">Cu(In 0.7Ga 0.3)Se 2
电沉积
Cu-In-Ga金属预制层
等离子体活化硒 相似文献
15.
p-CuIn 0.7Ga 0.3(Se (1?x)Te x) 2 type thin films were synthesized by thermal evaporation method on Mo coated glass substrates. To obtain Al/CuIn 0.7Ga 0.3(Se (1?x)Te x) 2/Mo Schottky diode structure for two compositions of x = 0.0 and 0.6, Al metal was evaporated on upper surface of CuIn 0.7Ga 0.3(Se (1?x)Te x) 2 as a front contact. Al/p-CuIn 0.7Ga 0.3(Se (1?x)Te x) 2/Mo structures were annealed temperature range from 150 °C to 300 °C for 10 min under vacuum. The electrical and dielectrical properties of Al/p-CuIn 0.7Ga 0.3(Se (1?x)Te x) 2 (CIGSeTe) Schottky barrier diodes (SBD) have been investigated. Capacitance–Voltage ( C– V) characteristics, Conductance–Voltage ( G/ w– V) characteristics and interface state density were studied in order to obtain electrical and dielectrical parameters. The effects of interface state density ( Nss), series resistance ( Rs), the dielectric constant ( ?′), dielectric loss ( ?″), dielectric loss tangent (tan δ), ac electrical conductivity ( σac) and carrier doping densities were calculated from the C– V and G/ w– V measurements and plotted as a function of annealing temperature. It was observed that the values of carrier doping density NA for annealing temperature at 150 °C decreased from 2.83 × 10 +15 cm ?3 to 2.87 × 10 +14 cm ?3 with increasing Te content from x = 0.0 to 0.6. The series resistance for x = 0.0 found to be between 10 and 75 Ω and between 50 and 230 Ω for x = 0.6 in the range of annealing temperature at 150–300 °C. 相似文献
16.
The magnetic properties of Y 2Fe 17−xGa x for 3≤ x≤7 and Gd 2Fe 17−xGa x for 5≤ x≤7 have been investigated using 57Fe Mössbauer spectroscopy. These compounds have the rhombohedral Th 2Zn 17 structure. X-ray diffraction analysis of aligned powders shows that the easy direction of magnetization is parallel to the c-axis in Y 2Fe 10Ga 7 and Gd 2Fe 10Ga 7 and is perpendicular to the c-axis in Y 2Fe 14Ga 3, Y 2Fe 12Ga 5, Gd 2Fe 12Ga 5 and Gd 2Fe 11Ga 6. Mössbauer studies indicate that those samples are ordered ferromagnetically. The 57Fe hyperfine field decreases with increasing Ga content. This decrease results from the decreased magnetic exchange interactions resulting from Ga substitution. The average isomer shift, δ, for R 2Fe 17−xGa x (R=Y and Gd) at room temperature is positive and the magnitude of δ increases with increasing Ga content. 相似文献
17.
We investigated the effect of Na incorporation on the electronic properties of polycrystalline CuIn 0.7Ga 0.3Se 2 thin films using scanning tunneling microscopy and spectroscopy. The tunneling spectra indicate a reduced in‐gap density of states at grain boundaries and reveal a downward band‐bending in Na‐rich grain boundaries with respect to the adjacent grains, in agreement with our conductive atomic force microscopy data. It thus appears that Na passivates deep‐level defects at grain boundaries and induces a downward band‐bending there. Moreover, we provide evidence that Na passivates mainly Cu vacancy related defects. We suggest that the grain‐boundary passivation, which reduces the recombination rate of photogenerated carriers, is at least of major importance in the well known Na‐induced improvement in the efficiency of the corresponding solar cells. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
18.
We report on a strong piezoresistive effect in GaAs/ In x Ga 1–x As/AlAs superlattice structures fabricated on a GaAs‐base cantilever. The measurements of the piezoresistive properties were performed for tensile strains by static pressure experiments. The maximum gauge factor (GF) for the GaAs/In x Ga 1–x As/AlAs epilayer can be estimated to 200, which is higher than the value of the gauge factor reported for Si transducers. Our results demonstrate a higher potential of GaAs/In x Ga 1–x As/AlAs superlattice structures for the development of piezoresistive sensors. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
19.
Specific features of the properties of Ga–P lattice vibrations have been investigated using the percolation model of a mixed Ga1 – xAl
x
P crystal (alloy) with zero lattice mismatch between binary components of the alloy. In contrast to other two-mode alloy systems, in Ga1 – xAl
x
P a percolation splitting of δ ~ 13 cm–1 is observed for the low-frequency mode of GaP-like vibrations. An additional GaP mode (one of the percolation doublet components) split from the fundamental mode is observed for the GaP-rich alloy, which coincides in frequency with the gap corresponding to the zero density of one-phonon states of the GaP crystal. The vibrational spectrum of impurity Al in the GaP crystal has been calculated using the theory of crystal lattice dynamics. Upon substitution of lighter Al for the Ga atom, the calculated spectrum includes, along with the local mode, a singularity near the gap with the zero density of phonon states of the GaP crystal, which coincides with the mode observed experimentally at a frequency of 378 cm–1 in the Ga1 – xAl
x
P (x < 0.4) alloy. 相似文献
20.
Se vapor pressures were measured by the dew point method for the binary system Ga 1·xSe x, 0.60 < x < 1.00 (Ga 2Se 3-Se), between 700 and 1050°C. The Se vapor pressure was found to decrease rapidly near x = 60 atomic% Se. The T- X and P- X liquidus curves are thermodymanically modelled by a regular associated solution model for the liquid phase, with the associate, Ga 2Se 3. The best fit to the data was obtained with 4000 cal/mole of Ga 2Se 3 for the regular solution interaction parameter and 0.10 for the degree of dissociation in the stoichiometric liquid ( x = 0.60). 相似文献
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