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1.
CuInGaSe2 thin films have been prepared by a low pressure metalorganic chemical vapor deposition technique using three precursors without additional Se. The properties of the resultant films have been examined by scanning electron microscopy, X-ray diffraction, micro-Raman scattering and absorption spectroscopy. 相似文献
2.
T. Eisenbarth T. Unold R. Caballero C.A. Kaufmann D. Abou-Ras H.-W. Schock 《Thin solid films》2009,517(7):2244-7316
A series of CuIn1 − xGaxSe2 solar cells with varied Ga content (0 ≤ x ≤ 1) was prepared using a three-stage co-evaporation process. The grain sizes of these devices vary with gallium content, exhibiting a maximum for approximately x = 0.2, which does not coincide with the maximum of the solar conversion efficiency observed between 0.34 < x < 0.37 for these devices.Admittance spectroscopy and drive-level capacitance profiling measurements were performed yielding a defect level with an activation energy of Ea = 0.1 eV which is independent of the amount of Ga and the grain size respectively. This defect closely resembles the N1 defect level reported in the literature. Only for relatively high Ga contents (x > 0.7) an additional defect appears. An equivalent circuit model describing a parallel connection of bulk and grain boundary capacitors allows us to conclude that the detected shallow defect is not predominantly located at the grain boundaries. 相似文献
3.
Zinc cadmium sulfide (ZnxCd1 − xS) heterojunction partner layer prepared with chemical bath deposition (CBD) has exhibited better blue photon response and higher current densities due to its higher bandgap than that of conventional cadmium sulfide (CdS) layer for CuIn1 − xGaxS2 (CIGS2) solar cells. CIGS2/ZnxCd1 − xS devices have also shown higher open circuit voltage, Voc indicating improved junction properties. A conduction band offset has been observed by J-V curves at various temperatures indicating that still higher Voc can be obtained by optimizing the conduction band offset. This contribution discusses the effect of variation of parameters such as concentration of compounds, pH of solution and deposition time during CBD on device properties and composition and crystallinity of film. Efficiencies comparable to CIGS2/CdS devices have been achieved for CIGS2/ZnxCd1 − xS devices. 相似文献
4.
CuIn1 − xGaxSe2 (CIGS) solar cells show a good spectral response in a wide range of the solar spectrum and the bandgap of CIGS can be adjusted from 1.0 eV to 1.7 eV by increasing the gallium-to-indium ratio of the absorber. While the bandgaps of Ga-rich CIGS or CGS devices make them suitable for top or intermediate cells, the In rich CIGS or CIS devices are well suited to be used as bottom cells in tandem solar cells. The photocurrent can be adapted to the desired value for current matching in tandem cells by changing the composition of CIGS which influences the absorption characteristics. Therefore, CIGS layers with different [Ga]/[In + Ga] ratios were grown on Mo and ZnO:Al coated glass substrates. The grain size, composition of the layers, and morphology strongly depend on the Ga content. Layers with Ga rich composition exhibit smaller grain size and poor photovoltaic performance. The current densities of CIGS solar cells on ZnO:Al/glass varied from 29 mA cm− 2 to 13 mA cm− 2 depending on the Ga content, and 13.5% efficient cells were achieved using a low temperature process (450 °C). However, Ga-rich solar cells exhibit lower transmission than dye sensitized solar cells (DSC). Prospects of tandem solar cells combining a DSC with CIGS are presented. 相似文献
5.
CuIn1 − xAlxSe2 (CIAS) thin films were grown by a two stage process. Cu, In and Al layers were sequentially evaporated and subsequently heated with elemental selenium in a quasi-closed graphite box. Different x values (0 ≤ x ≤ 0.6) were obtained by varying the Al and In precursor layers thicknesses. Selenization conditions such as Se amount provided during the selenization process were adjusted in order to optimize the film properties. Polycrystalline CuIn1 − xAlxSe2 thin films with chalcopyrite structure were obtained. Referred to CuInSe2 thin films the lattice parameters, the (112) orientation and the average crystallite size decreased and the band gap energy increased with increasing Al content. To optimize structural properties of the CIAS films a higher Se amount was required as the x value increased. The incorporation of Al changed the thin film morphology towards smaller grain sizes and less compact structures. 相似文献
6.
Sachin S. Kulkarni Galymzhan T. Koishiyev Neelkanth G. Dhere 《Thin solid films》2009,517(7):2121-2124
This paper describes the synthesis and characterization of CuIn1 − xGaxSe2 − ySy (CIGSeS) thin-film solar cells prepared by rapid thermal processing (RTP). An efficiency of 12.78% has been achieved on ~ 2 µm thick absorber. Materials characterization of these films was done by SEM, EDS, XRD, and AES. J-V curves were obtained at different temperatures. It was found that the open circuit voltage increases as temperature decreases while the short circuit current stays constant. Dependence of the open circuit voltage and fill factor on temperature has been estimated. Bandgap value calculated from the intercept of the linear extrapolation was 1.1-1.2 eV. Capacitance-voltage analysis gave a carrier density of 4.0 × 1015 cm− 3. 相似文献
7.
Parameterization of the electronic band structure of CuIn1−xGaxSe2 (x = 0, 0.5, and 1) demonstrates that the energy dispersions of the three uppermost valence bands [Ej(k); j = v1, v2, and v3] are strongly anisotropic and non-parabolic even very close to the Γ-point valence-band maximum Ev1(0). Also the lowest conduction band Ec1(k) is anisotropic and non-parabolic for energies ~ 0.05 eV above the band-gap energy. Since the electrical conductivity depends directly on the energy dispersion, future electron and hole transport simulations of CuIn1−xGaxSe2 need to go beyond the parabolic approximation of the bands. We therefore present a parameterization of the energy bands, the k-dependency of the effective electron and hole masses mj(k), and also an average energy-dependent approximation of the masses mj(E). 相似文献
8.
The present work studies the influence of the Ga content (x = Ga / (Ga + In)) in the absorber on the solar cell performance for devices using (PVD)In2S3-based buffers. Input to the hypothesis of the relative conduction band positions can be found in the evolution of the device parameters with x. For experiments with x between 0 and 0.5 devices using (PVD)In2S3-based buffers are compared to reference devices using (CBD)CdS. Both buffers give similar cell characteristics for narrow band gap absorbers, typically EgCIGSe < 1.1 eV. However, the parameters of the cells buffered with (PVD)In2S3 are degraded when the absorber gap is widened whereas (CBD)CdS reference devices are only slightly affected. Consequently, the solar cell efficiency is similar for both buffer layers at the lower x values and increases with x only in the case of (CBD)CdS. These evolutions are coherent with the existence of a conduction band cliff at the CIGSe/(PVD)In2S3 interface. 相似文献
9.
Application of the Sb-doping method to low-temperature (≤ 400 °C) processing of CuIn1 − xGaxSe2 − ySy (CIGS) solar cells is explored, using a hydrazine-based approach to deposit the absorber films. Power conversion efficiencies of 10.5% and 8.4% have been achieved for CIGS devices (0.45 cm2 device area) processed at 400 °C and 360 °C, respectively, with an Sb-incorporation level at 1.2 mol % (relative to the moles of CIGS). Significant Sb-induced grain size enhancement was confirmed for these low processing temperatures using cross-sectional scanning electron microscopy, and an average 2-3% absolute efficiency improvement was achieved in Sb-doped samples compared to their Sb-free sister samples. With Sb inclusion, the CIGS film grain growth temperature is lowered to well below 450 °C, a range compatible with flexible polymer substrate materials such as polyimide. This method opens up access to opportunities in low-temperature processing of CIGS solar cells, an area that is being actively pursued using both traditional vacuum-based as well as other solution-based deposition techniques. 相似文献
10.
J. Olejní?ek C.A. KamlerS.A. Darveau C.L. ExstromL.E. Slaymaker A.R. VandeventerN.J. Ianno R.J. Soukup 《Thin solid films》2011,519(16):5329-5334
CuIn1 − xAlxSe2 (CIAS) thin films (x = 0.06, 0.18, 0.39, 0.64, 0.80 and 1) with thicknesses of approximately 1 μm were formed by the selenization of sputtered Cu―In―Al precursors and studied via X-ray diffraction, inductively coupled plasma mass spectrometry and micro-Raman spectroscopy at room temperature. Precursor films selenized at 300, 350, 400, 450, 500 and 550 °C were examined via Raman spectroscopy in the range 50-500 cm− 1 with resolution of 0.3 cm− 1. Sequential formation of InxSey, Cu2 − xSe, CuInSe2 (CIS) and CIAS phases was observed as the selenization temperature was increased. Conversion of CIS to CIAS was initiated at 500 °C. For all CuIn1 − xAlxSe2 products, the A1 phonon frequency varied nonlinearly with respect to the aluminum composition parameter x in the range 172 cm− 1 to 186 cm− 1. 相似文献
11.
Clas Persson 《Thin solid films》2009,517(7):2374-7507
Green's functions modelling of the impurity induced effects in p-type CuIn1 − xGaxS2 and CuIn1 − xGaxSe2 (x = 0.0, 0.5, and 1.0) reveals that: (i) the critical active acceptor concentration for the metal non-metal transition occurs at Nc ≈ 1017-1018 cm− 3 for impurities with ionization energy of EA ≈ 30-60 meV. (ii) For acceptor concentrations NA > Nc, the hole gas of the metallic phase affects the band-edge energies and narrows the energy gap Eg = Eg0 − ΔEg. The energy shift of the valence-band maximum ΔEv1 is roughly twice as large as the shift of the conduction-band minimum ΔEc1. (iii) ΔEv1 depends strongly on the non-parabolicity of the valence bands. (iv) Sulfur based compounds and Ga-rich alloys have the largest shifts of their band edges. (v) A high active acceptor concentrations of NA = 1020 cm− 3 implies a band-gap narrowing in the order of ΔEg ≈ 0.2 eV, thus Eg = Eg0 − 0.2 eV, and an optical band gap of Egopt ≈ Eg0 − 0.1 eV. 相似文献
12.
S. Seyrling A. ChirilaD. Güttler F. PianezziP. Rossbach A.N. Tiwari 《Thin solid films》2011,519(21):7232-7236
CuIn1−xGaxSe2 absorbers for highest efficiency state-of-the-art solar cells are generally deposited by a sequential three-stage coevaporation process from elemental sources. We investigated the influence of the maximum copper concentration used during processing in the second stage of the growth process. The impact on the Ga grading in the deposited layer was measured by SIMS. The position and slope of the Ga grading profiles were optimized for high efficiency solar cells. Effects on the phases found in the absorber layer were investigated by Raman spectroscopy. The recorded spectra show the formation of a group III rich phase in layers grown at high maximum Cu contents. Best PV parameters were achieved for solar cells developed with absorbers grown with [Cu]/[In + Ga] = 1.05 at the end of the 2nd stage. 相似文献
13.
O. Aissaoui L. Bechiri N. Benslim X. Portier J.L. Doualan A. Otmani 《Thin solid films》2009,517(7):2171-2174
CuIn1 − xGaxTe2 thin films with x = 0, 0.5 and 1, have been prepared by flash evaporation technique. These semiconducting layers present a chalcopyrite structure. The optical measurements have been carried out in the wavelength range 200-3000 nm. The linear dependence of the lattice parameters as a function of Ga content obeying Vegard's law was observed. The films have high absorption coefficients (4 · 104 cm− 1) and optical band gaps ranging from 1.06 eV for CuInTe2 to 1.21 eV for CuGaTe2. The fundamental transition energies of the CuIn1 − xGaxTe2 thin films can be fitted by a parabolic equation namely Eg1(x) = 1.06 + 0.237x − 0.082x2. The second transition energies of the CuInTe2 and CuGaTe2 films were estimated to be: Eg2 = 1.21 eV and Eg2 = 1.39 eV respectively. This variation of the energy gap with x has allowed the achievement of absorber layers with large gaps. 相似文献
14.
Chalcopyrite CuIn1−xAlxSe2 (CIAS) thin films with an atomic ratio of Al/(In + Al) = 0.4 were grown by a two-stage process onto soda-lime glass substrates. The selenisation was carried out at different temperatures, ranging from 400 °C to 550 °C, for metallic precursors layers evaporated with two different sequences. The first sequence, C1, was evaporated with the Al as the last layer, while in the second one, C2, the In was the last evaporated element. The optical, structural and morphological characterisations led to the conclusion that the precursors sequence determines the crystallisation pathway, resulting in C1 the best option due to the homogeneity of the depth distribution of the elements. The influence of the selenisation temperature was also studied, finding 540 °C as the optimum one, since it allows to achieve the highest band gap value for the C1 sequence and for the given composition. 相似文献
15.
Ramakanta Naik 《Thin solid films》2010,518(19):5437-5441
In this paper, we report results of the optical properties of thermally deposited As2 − xS3 − xSbx thin films with x = 0.02, 0.07, 0.1 and 0.15. We have characterized the deposited films by Fourier Transform Infrared, Raman and X-ray photoelectron spectroscopy (XPS). The relationship between the structural and optical properties and the compositional variation were investigated. It was found that the optical bandgap decreases with increase in Sb content. The XPS core level spectra show a decrease in As2S3 percentage with increase in Sb content. This is confirmed from the shifting of the Raman peak from AsS3 vibrational mode towards SbS3 vibrational mode. 相似文献
16.
CuInGa precursor thin films were deposited using a CuGa (75-25 at.%) and an In 3″ diameter target material simultaneously by RF magnetron sputtering. The precursor films were deposited on Si and glass substrates at − 80 °C and room temperature, and characterized by Rutherford backscattering spectroscopy, Auger electron spectroscopy, scanning electron microscopy, atomic force microscopy and X-ray diffraction. The effects of gun power density and substrate temperatures on resulting precursor film properties were investigated. Precursor films deposited at − 80 °C have a smooth morphology with a 75% reduction in all roughness values and are more dense and homogeneous in structure compared to precursors deposited at room temperature. Therefore these precursors will result in better selenization process reproducibility. 相似文献
17.
Cd1 − xZnxO nanocrystalline thin films with rock-salt structure were obtained through thermal decomposition of Cd1 − xZnxO2 (x = 0, 0.37, 0.57, 1) thin films which were electrodeposited from aqueous solution at room temperature. X-ray diffraction results showed that the Zn ions were incorporated into rock salt-structure of CdO and the crystal lattice parameters decreased with the increase of Zn contents. The bandgaps of the Cd1 − xZnxO thin films were obtained from optical transmission and were 2.40, 2.51, 2.63 and 3.25 eV, respectively. 相似文献
18.
Philipp M. Leufke Ajay Kumar MishraAndré Beck Di Wang Christian Kübel Robert KrukHorst Hahn 《Thin solid films》2012,520(17):5521-5527
Studies on large-distance sputtering as an effective alternative to molecular beam epitaxy, pulsed laser deposition or off-axis sputtering for the deposition of epitaxial La1 − xSrxMnO3 (LSMO) thin films, are reported. The focus of this study is on the quality of the samples and their structural and magnetic properties. The dependence of the characteristics of the LSMO films on the sputtering mode (rf, dc) and the sputtering parameters, in particular on the oxygen partial pressure is established and discussed. It is shown that large-distance sputtering can provide high quality LSMO thin films without the need for post-annealing. 相似文献
19.
The dielectric function of bulk CuAl1 − xInxSe2 with composition x varying from x = 0.07 to x = 0.6 were studied over the photon energy region 1.0-6.0 eV at room temperature by spectroscopic ellipsometry. Information on the inter-band optical transitions was obtained from the results of the standard critical point analysis of the obtained dielectric function. With increasing Indium content, all spectral features of the obtained dielectric functions were found to gradually shift towards lower energies. The details of this shift for each critical point retrieved from the obtained dielectric function were disclosed. A compositional dependence of the optical transitions in Γ point of the Brillouin zone was verified to be strong. Such dependence for N and T points turned out to be weak by comparison. The later fact was accounted for a small compositional shift of the conduction band states in N and T points as compared to Γ point. 相似文献
20.
We have investigated the structural properties of Si1 − xGex nanocrystals formed in an amorphous SiO2 matrix by magnetron sputtering deposition. The influence of deposition parameters on nanocrystal size, shape, arrangement and internal structure was examined by X-ray diffraction, Raman spectroscopy, grazing incidence small angle X-ray scattering, and high resolution transmission electron microscopy. We found conditions for the formation of spherical Si1 − xGex nanocrystals with average sizes between 3 and 13 nm, uniformly distributed in the matrix. In addition we have shown the influence of deposition parameters on average nanocrystal size and Ge content x. 相似文献