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《Current Applied Physics》2015,15(12):1563-1567
To anticipate the initial phosphorus diffusion parameters of silicon solar cells process fabrication, we report in this paper an overview of our experiments on silicon n+-emitters passivation by means of rapid thermal silicon oxide/silicon nitride stack. The process-induced changes have been evaluated and explained. We found that 900 °C and 80 s were the appropriate process parameters to grow 10 nm silicon oxide. Investigation of the effect of this oxidation on n+ multicrystalline silicon emitters revealed a large decrease (more than 25%) of the sheet resistance and around 12% increase of the junction depth. The experiments also revealed that the passivation effect of the optimal silicon oxide/silicon nitride stack is efficient only for higher emitter quality. In addition, we found that this stack reduces the surface reflection more than the optimal single silicon nitride layer. 相似文献
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E. Pin?ík H. Kobayashi M. Takahashi L. Ortega M. Jergel 《Applied Surface Science》2008,254(24):8059-8066
Formation of defect states on semiconductor surfaces, at its interfaces with thin films and in semiconductor volumes is usually predetermined by such parameters as semiconductor growth process, surface treatment procedures, passivation, thin film growth kinetics, etc. This paper presents relation between processes leading to formation of defect states and their passivation in Si and GaAs related semiconductors and structures. Special focus is on oxidation kinetics of yttrium stabilized zirconium/SiO2/Si and Sm/GaAs structures. Plasma anodic oxidation of yttrium stabilized zirconium based structures reduced size of polycrystalline silicon blocks localised at thin film/Si interface. Samarium deposited before oxidation on GaAs surface led to elimination of EL2 and/or ELO defects in MOS structures. Consequently, results of successful passivation of deep traps of interface region by CN− atomic group using HCN solutions on oxynitride/Si and double oxide layer/Si structures are presented and discussed. By our knowledge, we are presenting for the first time the utilization of X-ray reflectivity method for determination of both density of SiO2 based multilayer structure and corresponding roughnesses (interfaces and surfaces), respectively. 相似文献
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V.A. Terekhov S.Yu. Turishchev V.M. Kashkarov E.P. Domashevskaya A.N. Mikhailov D.I. Tetelbaum 《Physica E: Low-dimensional Systems and Nanostructures》2007,38(1-2):16
Silicon ions were implanted into the films of silicon oxide obtained by thermal oxidation of silicon wafers in a damp oxygen. Accumulation of the implantation dose was performed either in one step or cyclically in step-by-step mode, and after each stage of implantation the samples were annealed in a dry nitrogen. The second series of the samples differed from the first one by the formation of SiO2 matrix that included additional annealing in the air at 1100 °C for 3 h before ion implantation. X-ray absorption near edge structure (XANES) was obtained with the use of synchrotron radiation. Two absorption edges were observed in all of Si L2,3-spectra. One of them is related to elementary silicon while the other one-to silicon in SiO2. The fine structure of the first one indicates the formation of nanocrystalline silicon nc-Si in SiO2 matrix. Its atomic and electron structure depends on the technology of formation. For both series of samples, a cyclical accumulation of the total dose Φ=1017 cm−2 (for the total time of annealing—2 h) resulted in the appearance of more distinct structure in the range of absorption edge for the elementary silicon as compared with the case of single-step accumulation dose. In the more “dense” oxide of the samples from the second series, the probability of formation of silicon nanocrystals in a thin near-surface region of the implanted layer was reduced. These results can be interpreted with the account of the previously obtained photoluminescence, Raman scattering and electron microscopy data for these samples. 相似文献
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It is demonstrated that the application of an ultrathin aluminum oxide (Al2O3) capping film can improve the level of silicon surface passivation obtained by low‐temperature synthesized SiO2 profoundly. For such stacks, a very high level of surface passivation was achieved after annealing, with Seff < 2 cm/s for 3.5 Ω cm n‐type c‐Si. This can be attributed primarily to a low interface defect density (Dit < 1011 eV–1 cm–2). Consequently, the Al2O3 capping layer induced a high level of chemical passivation at the Si/SiO2 interface. Moreover, the stacks showed an exceptional stability during high‐temperature firing processes and therefore provide a low temperature (≤400 °C) alternative to thermally‐grown SiO2. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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The perturbed γ–γ angular correlation method has been employed to study indium-impurity pairs in silicon, consisting of the probe atom (111In/111Cd) and several group-VI donors. Such pairs can be identified via the interaction between the quadrupole moments of the probe nucleus and the electric field gradient (EFG) associated with the formed defect complex. A new quadrupole interaction frequency (QIF) of νQ=444(1) MHz (η=0) is measured at T=293 K in Te implanted silicon after annealing the sample above 700 K. The complex is attributed to the In-Te pair along 〈100〉-crystal axis in silicon. In addition, the temperature dependence of the QIF characterizing the pair has also been studied. The implantations of S and Se could not lead to the formation of observable complexes despite similar treatment of all samples. PACS 61.72.-y; 76.80.+y; 61.72.Cc 相似文献
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In this work, anodic porous alumina thin films with pores in the nanometer range are grown on silicon by electrochemistry and are used as masking material for the nanopatterning of the silicon substrate. The pore diameter and density are controlled by the electrochemical process. Through the pores of the alumina film chemical oxidation of the silicon substrate is performed, leading to the formation of regular arrays of well-separated stoichiometric silicon dioxide nanodots on silicon, with a density following the alumina pores density and a diameter adjustable by adjusting the chemical oxidation time. The alumina film is dissolved chemically after the SiO2 nanodots growth, revealing the arrays of silicon dioxide dots on silicon. In a next step, the nanodots are also removed, leaving a nanopatterned bare silicon surface with regular arrays of nanopits at the footprint of each nanodot. This silicon surface structuring finds interesting applications in nanoelectronics. One such application is in silicon nanocrystals memories, where the structuring of the oxidized silicon surface leads to the growth of discrete silicon nanocrystals of uniform size. In this work, we examine the electrical quality of the Si/SiO2 interface of a nanostructured oxidized silicon surface fabricated as above and we find that it is appropriate for electronic applications (an interface trap density below 1–3×1010 eV−1 cm−2 is obtained, indicative of the high quality of the thermal silicon oxide). 相似文献
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Amorphous silicon nitride (a-SiNx) films were deposited using plasma-enhanced chemical-vapor deposition (PECVD) and subsequently, thermal annealing processes were performed at 700-1000 °C in the ultra-high vacuum (UHV) condition. A strong photoluminescence (PL) peak induced by luminescent defect centers was observed at 710 nm for the as-deposited sample. When the sample was annealed at 700-1000 °C, the PL peak intensity became about 3-12 times stronger with no shift of the PL peak. To investigate the origin of the change in PL peak intensity after the thermal annealing, Si 2p and N 1s core-level spectra were systematically analyzed by high-resolution photoemission spectroscopy (HRPES) using synchrotron radiation. In particular, N 1s spectra were decomposed with three characteristic nitrogen-bonding states. It is revealed that the nitrogen bonding state with N-Si and NSi2 configurations (denoted as N3) contributes mainly to the change in PL peak intensity. We note that luminescent nitrogen related defect centers such as N4+ and N2° are localized in the state N3. Detailed analysis of the experimental results shows that the state N3 is located in the interface bounded by the region of the nano-sized stoichiometric silicon nitride Si3N4 (denoted as N1) and is considerably influenced by the thermal annealing, which is an appropriate process to cause strong photoluminescence of the related samples as mentioned above. 相似文献
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Stacks of aluminum oxide and silicon nitride are frequently used in silicon photovoltaics. In this Letter, we demonstrate that hydrogenated aluminum nitride can be an alternative to this dual‐layer stack. Deposited on 1 Ω cm p‐type FZ silicon, very low effective surface recombination velocities of 8 cm/s could be reached after firing at 820 °C. This excellent passivation is traced back to a high density of fixed charges at the interface of approximately –1 × 1012 cm–2 and a very low interface defect density below 5 × 1010 eV–1 cm–2. Furthermore, spectral ellipsometry measurements reveal that these aluminum nitride layers have ideal optical properties for use as anti‐reflective coatings. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Linear defect modes in one-dimensional photonic lattices are studied theoretically. For negative (repulsive) defects, various localized defect modes are found. The strongest confinement of the defect modes appears when the lattice intensity at the defect site is nonzero rather than zero. When launched at small angles into such a defect site of the lattice, a Gaussian beam can be trapped and undergo snake oscillations under appropriate conditions. 相似文献
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We investigated an influence of hydrogen plasma treatment on electrical properties of shaped silicon polycrystals. Hydrogen penetration into polycrystalline silicon is demonstrated to depend on the state of the crystal (as-grown or annealed) and type of grain boundary (general or weakly deviated from special orientations). It is found that interaction of atomic hydrogen with grain boundaries can result not only in decrease of their electrical activity, but also in increase of potential barrier height at relatively high (more than 2 × 1018 cm–2) doses of incorporated hydrogen. This phenomenon is explained by a phenomenological model which takes into account passivation of grain boundary dangling bonds and boron atoms in the bulk as two main mechanisms controlling hydrogenation effect. 相似文献
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Johannes Ziegler Martin Otto Alexander N. Sprafke Ralf B. Wehrspohn 《Applied Physics A: Materials Science & Processing》2013,113(2):285-290
Thin aluminum oxide layers deposited on silicon by thermal atomic layer deposition can be used to reduce the electronic recombination losses by passivating the silicon surfaces. To activate the full passivation ability of such layers, a post-deposition annealing step at moderate temperatures (≈400 °C, duration≈30 min) is required. Such an annealing step is commonly done in an oven in air, nitrogen, or forming gas atmosphere. In this work, we investigate the ability to reduce the duration of the annealing step by heating the silicon wafer with a microwave source. The annealing time is significantly reduced to durations below 1 min while achieving effective minority carrier lifetimes similar or higher to that of conventionally oven-annealed samples. 相似文献
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Optical absorption coefficient spectra of thin silicon films were precisely investigated using a simple reflectance system with total reflectance mirrors placed on the rear side of samples in order to cancel an interference effect in a range between 1.1 eV and 3 eV. The absorption coefficient decreased according to crystallization as the laser energy increased and it got similar to that of single crystalline silicon in the range of 1.7 eV 3 eV. However, the absorption coefficient was higher than 102 cm–1 in the photon energy lower than 1.3 eV. This probably results from band tail states caused by defect states localized at grain boundaries in the crystallized films. 2.5%-phosphorus doped laser crystallized silicon films had a high optical absorption coefficient ( > 104 cm–1) in the low photon energy range (1.1 eV 1.7 eV) caused by free carriers produced from the dopant atoms activated in the silicon films. The experimental results gave the carrier density of 1.3 × 1021 cm3 and the carrier mobility of 20 cm2/Vs. 相似文献
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J. Weber R. J. Davis H. -U. Habermeier W. D. Sawyer M. Singh 《Applied Physics A: Materials Science & Processing》1986,41(3):175-178
We report on a photoluminescence study of silicon samples subjected to different dry etching processes. Several luminescence lines, known from defects produced by high-energy irradiation, manifest damage of the crystalline material. Noble gas ion beam etching (using Ne+, Ar+, Kr+, and Xe+) with ion energies as low as 400 eV produces characteristic luminescence lines which correspond to defects within a 200–300 Å thick surface layer. Incorporation of carbon during CF4 reactive ion etching produces the familiar G-line defect. The G-line photoluminescence intensity in our samples is directly correlated with the substitutional carbon concentration, as determined by infrared absorption measurements before the etch process; we therefore suggest that a simple method to determine the substitutional carbon concentration in a crystalline silicon sample is a standard dry etching process and a comparison of the resulting G-line photoluminescence intensity to a calibrated sample. The sensitivity of this method seems to be better than 1014 carbon atoms/cm3. 相似文献
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Acceleration and mitigation of carrier‐induced degradation in p‐type multi‐crystalline silicon 下载免费PDF全文
D. N. R. Payne C. E. Chan B. J. Hallam B. Hoex M. D. Abbott S. R. Wenham D. M. Bagnall 《固体物理学:研究快报》2016,10(3):237-241
Recently, a new carrier‐induced defect has been reported in multi‐crystalline silicon (mc‐Si), and has been shown to be particularly detrimental to the performance of passivated emitter and rear contact (PERC) cells. Under normal conditions, this defect can take years to fully form. This Letter reports on the accelerated formation and subsequent passivation of this carrier‐induced defect through the use of high illumination intensity and elevated temperatures resulting in passivation within minutes. The process was tested on industrial mc‐Si PERC solar cells, where degradation after a 100 hour stability test was suppressed to only 0.1% absolute compared to 2.1% for non‐treated cells. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
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V. P. Veleshchuk O. V. Lyashenko Yu. A. Myagchenko R. G. Chuprina 《Journal of Applied Spectroscopy》2004,71(4):553-557
The dependence of the spectral position of the electroluminescence bands of epitaxial light-emitting diode n
+–n–p structures (GaAs0.15P0.85) on the density of a direct heterojunction current at different successive instants of time — before an acoustic emission and after it — has been revealed. The shifts of the electroluminescence bands accompanied by acoustic emission can be divided into three types according to the density of the current: (1) short-term shifts due to relaxation of the defect structure of a sample — at relatively low currents, (2) the magnitude of the reverse shift being determined by the current density — at large currents, and (3) formation of an IR band (1.5–1.1 eV) with irreversible degradation changing in the red (1.75 eV) and green (2.19 eV) bands of the electroluminescence spectrum — at ultrahigh currents (100–200 A/cm2). 相似文献
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Plasma enhanced atomic layer deposition of gallium oxide on crystalline silicon: demonstration of surface passivation and negative interfacial charge 下载免费PDF全文
Herein we report on the passivation of crystalline silicon by gallium oxide (Ga2O3) using oxygen plasma as the oxidizing reactant in an atomic layer deposition (ALD) process. Excess carrier lifetimes of 2.1 ms have been measured on 1.75 Ω cm p‐type silicon, from which a surface recombination current density J0 of 7 fA cm–2 is extracted. From high frequency capacitance‐voltage (HF CV) measurements it is shown that, as in the case of Al2O3, the presence of a high negative charge density Qtot/q of up to –6.2 × 1012 cm–2 is one factor contributing to the passivation of silicon by Ga2O3. Defect densities at midgap on the order of ~5 × 1011 eV–1 cm–2 are extracted from the HF CV data on samples annealed at 300 °C for 30 minutes in a H2/Ar ambient, representing an order of magnitude reduction in the defect density compared to pre‐anneal data. Passivation of a boron‐diffused p+ surface (96 Ω/□) is also demonstrated, resulting in a J0 of 52 fA cm–2. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献