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The paper studies the gettering properties of nickel clusters in the silicon lattice. The gettering properties of nickel clusters were studied in various states, i.e., in original (reference) samples, as well as in samples with additionally doped interstitial and lattice site impurity atoms of sulfur and manganese. The electrophysical and photoelectric parameters were studied using modern instrumentation: INFRAM-I-type infrared microscope, IKS-21 and scanning electron microscope SEM (Oxford Instruments ZEISS EVOMA10), IKS-21. A new technology has also been proposed that makes it possible to getter harmful impurities; it is recommended for widespread use in the electronics industry and scientific research institutes for the production of materials with stable parameters and the development of fundamentally new devices. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Processing of Materials / Elektronnaya Obrabotka Materialov is the property of Institute of Applied Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The research results present the influence of nickel impurities introduced by diffusion into monocrystalline silicon on the characteristics of solar cells (SCs). It is established that doping with nickel atoms makes it possible to increase the lifetime of the MCCs in the material by up to a factor of two and the efficiency of SCs by 20–25%. It is shown that the distribution of nickel clusters in the volume of the material is almost uniform, and their size does not exceed 0.5 μm. The concentration of clusters in the volume is ~1011–1013 cm–3; and in the near-surface layer, ~1013–1015 cm–3. The physical mechanisms of the influence of the bulk and near-surface clusters of nickel atoms on the efficiency of silicon SCs are revealed. It is experimentally established that the decisive role in increasing their efficiency is played by the processes of gettering of recombination-active technological impurities by nickel clusters, occurring in the nickel-enriched front surface region of the SCs. [ABSTRACT FROM AUTHOR]

An assessment of the bulk material quality of industrial Czochralski (Cz) grown phosphorus‐doped n‐type silicon (Si) wafers along an ingot is reported. The minority charge carrier lifetimes of the Cz‐Si wafer bulk before and after phosphorous (POCl3) diffusion gettering are assessed, by applying room‐temperature superacid surface passivation to avoid any additional gettering or hydrogenation effect. A substantial increase in the bulk lifetime of all of the n‐type Cz‐Si wafers along the ingot is observed, indicating the effectiveness of a gettering step for such wafers and the presence of getterable metallic impurities in these wafers. By experimentally monitoring the lifetime changes upon a gettering anneal and simulating the gettering kinetics based on different metal diffusivities, iron is identified to be a limiting defect, at least for the wafers from the tail part of the ingot. A dissolved iron concentration of (8±2) ×1011 cm−3$\left(\right. 8 \pm 2 \left.\right) \textrm{ } \times \left(10\right)^{11} \left(\text{ cm}\right)^{- 3}$ is estimated from the bulk lifetimes of the tail wafers. This lifetime kinetics approach is also a demonstration of a new method to identify iron, or other getterable metals with moderate diffusivities such as chromium, in n‐type silicon wafers. [ABSTRACT FROM AUTHOR]

This study demonstrates that the concentration of nickel atoms near the surface of solar cells is 2-3 orders of magnitude higher than in the bulk material, significantly enhancing the gettering rate at the surface. Using IR-microscopy, SEM, and SIMS, we found that the surface density of nickel clusters is approximately 106-107 cm-2, with an average cluster diameter of 20-100 nm and a cluster concentration of 1011±1015 cm-3 Experimental results revealed that nickel clusters on the surface of silicon samples contain a substantial amount of oxygen and recombination impurities (Cu, Fe, Cr), indicating excellent gettering properties. We identified the physical mechanisms underlying the effects of nickel impurity atom diffusion and additional thermal annealing on the state of nickel atoms near the surface and base of the solar cells. Physical models were developed for the structure of nickel atom clusters in silicon and for the gettering process of fast-diffusing impurities by these clusters. The binding energy of fast-diffusing impurity atoms with a nickel cluster was estimated to be approximately 1.39 eV. Calculations indicated that nickel doping can increase the lifetime of minority charge carriers by a. factor of 2-4, and experimental results confirmed an increase in the lifetime of minority charge carriers by up to a. factor of 2. These findings highlight the potential of nickel doping to enhance the performance and efficiency of silicon-based solar cells, offering a promising avenue for future research and development in photovoltaic technology. [ABSTRACT FROM AUTHOR]

It was demonstrated that the concentration of nickel atoms near the surface of solar cells (SCs) is higher by 2–3 orders of magnitude in comparison with the bulk material, resulting in a significantly increased gettering rate in the former case. Experiments determined the optimal gettering conditions for nickel clusters (nickel diffusion temperature 800–850°C and additional thermal annealing temperature 750–800°C) and the structure of a silicon SC that enhances its efficiency by 25–30% in comparison with the reference structure. Physical mechanisms were identified for the effect of the diffusion of nickel impurity atoms and additional thermal annealing on the state of nickel atoms near the surface and the SC base and, consequently, on SC parameters. Physical models were developed for the structure of a cluster of nickel atoms in silicon and for the gettering process of fast-diffusing impurities by clusters of nickel atoms. The binding energy of fast-diffusing impurity atoms with a nickel cluster was estimated to be approximately 1.39 eV. Calculations showed that nickel doping can increase the minority carrier lifetime and the collection coefficient by factors of 2–4 and 1.4–2, respectively. Experiments demonstrated a twofold increase in minority carrier lifetime and a 25–30% improvement in the efficiency of SCs. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Processing of Materials / Elektronnaya Obrabotka Materialov is the property of Institute of Applied Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The formation of clusters of impurity atoms in the crystal lattice of semiconductor materials is of great interest. The formation of nanoclusters with controlled parameters in the lattice of semiconductor materials can serve as the basis for the technology of creating and obtaining bulk nanostructured semiconductor material. This paper shows the experimental results obtained, as well as the proposed physical model of the structure of nickel atomic clusters. It is shown that the clusters move and migrate in the crystal lattice of monosilicon with an anomalously high diffusion coefficient of about c (D ~ 10-9 cm2/s at T = 800°C). The structural composition of clusters of impurity atoms is determined, its structure and the mechanism of migration in the crystal lattice are proposed. Thus, it was found that it is possible to control the state of impurity atom clusters in the silicon crystal lattice, obtaining a new type of semiconductor materials with unique functional and properties using the cluster migration process. This makes it possible to create a new class of photonic materials with bulk superlattices based on semiconductors with ordered clusters, which has unique functionality for creating optoelectronic, nanoelectronic, photoelectric devices and sensors of physical quantities of a new generation. [ABSTRACT FROM AUTHOR]

The results of this study show that creation of clusters from impurity nickel atoms almost completely suppresses generation of thermal donors within the temperature range 450 to 1200 °C. The composition of these clusters was determined using the technique of energy dispersive X-ray spectroscopy, which revealed that the typical cluster consists of silicon atoms (65%), nickel atoms (15%) and oxygen atoms (19%). Based on the experimental results, the authors have suggested that the nickel atoms intensively perform the role of getter for oxygen atoms in the course of clusterization. It was shown that the additional doping of silicon with nickel at T = 1100...1200 °C enables to ensure a sufficiently high thermal stability of its electrical parameters within a wide temperature range. [ABSTRACT FROM AUTHOR]

This work presents results of a laboratory‐scale interdigitated back contact (IBC) solar cell with an independently measured efficiency of 25.0%, featuring open‐circuit voltage of 716 mV, short‐circuit current of 43.0 mA.cm−2 and fill factor of 81.0%. Notably, the high efficiency was achieved based on significant improvements resulting from the optimised cell structure, excellent SiO2‐SiNx‐SiOx (ONO) surface passivation, detailed bulk lifetime management strategy and improved random pyramid texturing. Experimental details and analysis of the individual improvements over prior work are presented in‐depth. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the influence of an annealing process at 500 °C for 30 min. after emitter diffusion of multi-crystalline solar cells was investigated. Neighboring sister wafers from a silicon ingot were processed using light doped emitter (LDE) and low temperature annealing (LTA). Emitter profiles measured by Electrochemical Capacitance Voltage (ECV) showed that there is no obvious difference between LDE and LTA due to the lower annealing temperature. The lifetime and iron concentration measurement indicated that the gettering of LTA diffusion is much better than LDE. Therefore, the solar cell efficiency of LTA was up to 19.01%, which is 0.28%abs higher than LDE due to the higher open circuit voltage (Voc) and short-circuit current (Isc). The Internal Quantum Efficiency (IQE) measurement with better long wavelength response showed the wafer quality was much improved after LTA diffusion. To further investigate diffusion gettering performance, light-induced-degradation (LID) was analyzed both for LDE and LTA diffusion. The LID of LDE diffusion with 1.15%rel. is obviously higher than LTA diffusion of 0.46%rel., attributing to the higher iron concentration of LDE diffusion emitter to result in higher iron-boron pair dissociation. [ABSTRACT FROM AUTHOR]

The polysilicon gettering behavior of iron (Fe) and copper (Cu) in highly boron doped silicon was studied under isothermal annealing with and without the presence of an electric field. Depth profiles of Fe and Cu in the polysilicon were obtained by dynamic secondary ion mass spectrometry. Enhanced gettering as a result of the electric field can be attributed to the drift-behavior of Fe and Cu over thermal diffusion at elevated temperature. While the polysilicon-silicon interfacial segregation acted against the back-diffusion of Cu, the same was not observed for Fe. About 61% of Cu and 35% of Fe were trapped in polysilicon after 2 days owing to strong interfacial segregations. [ABSTRACT FROM AUTHOR]

Highlights: [•] Gettering of molybdenum and tungsten is demonstrated. [•] Carbon implantation is effective in gettering, silicon implantation is not. [•] Extended defects are ineffective in gettering. We suggest a role of tensile strain. [•] Gettering is limited by impurity diffusion to the gettering regions. [•] Improvement of image sensor devices with carbon gettering was demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, the influence of oxygen precipitates in the bottom part of multicrystalline silicon ingots on the metal diffusion has been studied. According to the well known haze test, an experimental setup for the measurement of diffusion velocity at 700°C was developed, in which the copper was detected using Total Reflection X-ray Fluorescence. Differences in the diffusion velocity and the gettering amount for copper in samples with low-oxygen and high-oxygen were observed. Thus gettering efficiency seems to be dependent on oxygen content. Metal precipitates detected were found to contain Si, O and Cu. Since these precipitates appear along grain boundaries, it is assumed that grain boundaries act as a diffusion channel. As a consequence, oxygen precipitates located at the grain boundary should be most effective for intrinsic gettering. The results of these studies are encouraging since they imply that an optimized oxygen precipitate concentration in the bottom zone of a multicrystalline silicon ingot can be used as an effective intrinsic diffusion barrier. [Copyright &y& Elsevier]

Abstract: The effects of boron diffusion were investigated on electronic grade n-type single- and multicrystalline silicon wafers for solar cells application. Doped p+-layers were formed using specific spin-on dopant (SOD) source annealed in a tube furnace. Homogeneous diffused layers with sheet resistance values of 70Ω/sq were achieved on large area silicon wafers. Bulk electrical properties were investigated measuring the effective carrier lifetime after the diffusion step. A significant degradation of the bulk electrical properties was observed using the SOD technique. Unlike for the single-crystalline silicon, it was determined that this effect was not due to an interstitial iron contamination originating from the SOD, but rather by the thermal degradation of the material. Boron diffusion was followed by a phosphorous diffusion sequence, necessary in the fabrication process for the formation of the back surface field. This additional step leads to an improvement of effective lifetime values due to an efficient gettering of the impurities. Finally, bulk carrier lifetimes from 100μs to over 300μs were deduced on n-type multicrystalline silicon after boron and phosphorus diffusion. This underlines the potential of this material for photovoltaic application and its stability after high temperature treatments provided that a gettering step is included after the boron diffusion step. [Copyright &y& Elsevier]

Abstract: A procedure to discriminate the recombination in the bulk and highly doped layers is presented in this paper. It is based on the photoconductance decay technique. First the effective lifetime is measured for the whole sample, and then the recombinant surfaces are chemically etched and the bulk lifetime is measured by itself. This method has been applied to determine the recombination associated to Al diffusion in silicon wafers after several drive-in processes. Best values are 2000 cm/s on 1.6 Ωcm p-type wafers, obtained after driving 3 μm Al at 1050 °C for 3 h in a conventional furnace. After some processes they have also been measured effective recombination velocities over 10,000 cm/s. An insufficient BSF effect cannot explain such high values in those cases, and other questions like an insufficient gettering of impurities must be considered. [Copyright &y& Elsevier]

Polysilicon/oxide (poly-Si/SiO x) passivating contacts are a promising technology for the next-generation of high-efficiency silicon solar cells. The structure can be realised by a range of fabrication techniques, which can induce very different impurity gettering effects during the formation process. Understanding the different gettering effects will enable tailored solutions to optimise the gettering efficiency in device fabrication. This paper demonstrates a method to separately quantify the impact of each component on the overall gettering effect of the poly-Si/SiO x passivating contact structures. These components consist of the heavily doped poly-Si layer, in terms of its gettering strength; the SiO x interlayer, regarding its potential blocking effect for slowing down the diffusion of impurities; and the dopant in-diffused surface regions of the silicon wafer bulk directly below the SiO x interlayer, which may have a small additional gettering effect due to heavy doping. Phosphorus in-situ doped poly-Si layers from plasma-enhanced chemical vapour deposition (PECVD), coupled with SiO x interlayers from different growth techniques, were used to demonstrate the method. The experimental and simulation results confirm that the heavily doped poly-Si layer acts as the main gettering sink and the presence of different SiO x interlayers determines the overall gettering rate. For the ultrathin SiO x interlayers studied in this work, which have a similar thickness but different stoichiometry, a standard thermally grown SiO x demonstrates the strongest blocking effect, followed by a chemically grown SiO x from hot nitric acid, and a thermal SiO x of a reduced stoichiometry (grown in a pure nitrogen ambient) demonstrates practically no blocking effect. • A method to separate and quantify the impact of each component on the overall gettering effect of polysilicon/oxide. • Component 1: Heavily doped polysilicon layer, the main gettering sink. • Component 2: Ultrathin silicon oxide interlayer, a diffusion barrier that slows down the overall gettering rate. • Component 3: In-diffused crystalline silicon surface region, which may have a small gettering effect due to heavy doping. • PECVD in-situ P-doped polysilicon layers, with various oxide interlayers, are used to demonstrate the method. • Different blocking effects of the oxide interlayers can be quantified through fitting experimental kinetics by simulation. • Experimental gettering results after a typical structure formation process can be well reproduced by simulation. [ABSTRACT FROM AUTHOR]

We have made an investigation of the surface oxide effects on nanocavity formation in hydrogen implanted silicon and the influence of resultant nanocavities on diffusion and gettering of implanted silver atoms. A wafer with a 200-nm SiO2 surface layer was implanted with 22.5 keV H ions to a dose of 1 × 1017 cm-2, yielding the concentration peak of implanted H ions at ∼140 nm below the SiO2/Si interface. Subsequently, two sets of Si samples were prepared, depending on whether the oxide layer was etched off before (Group-A) or after (Group-B) post-H-implantation annealing. As evidenced by transmission electron microscopy, Group-A samples exhibited an array of large-sized nanocavities in hexagon-like shape, extending from the surface to the depth ∼140 nm, whereas a narrow band of sphere-shaped nanocavities of small size was present around 140 nm below the surface in Group-B samples. These Si samples with pre-existing nanocavities were further implanted with Ag ions in the surface region (∼40 nm projected range) and post-Ag-implantation annealing was conducted in the temperature range between 600 and 900 °C. Measurements based on Rutherford backscattering spectroscopy revealed much different behaviors for Ag redistribution and defect accumulation in these two sets of samples. Compared to the case for Group-B Si, Group-A Si exhibited a lower concentration of residual defects and a slower kinetics in Ag diffusion as well. We discuss the role of thick surface oxide in point defect generation and recombination, and the consequence on nanocavity formation and defect retention in Si. The properties of nanocavities, e.g., their depth distribution, size, and even shape, are believed to be responsible for the observed disparities between these samples, including an interesting contrast of surface vs. bulk diffusion phenomena for implanted Ag atoms. [ABSTRACT FROM AUTHOR]

Ion diffusion and gettering in YBCO oxides were studied, The experiment was carried out by implanting Si or Ni ions into epitaxial YBCO films and subsequently annealing the samples at different temperatures ranging from 450/spl deg/C to 1050/spl deg/C. Secondary ion mass spectroscopy (SIMS) analysis was used to determine ion profiles. At an annealing temperature of 750/spl deg/C, the silicon ions started to getter towards the peak of the silicon concentration, which has the maximum concentration. This gettering process continued annealing temperature was increased and reached the maximum at 850/spl deg/C. Further increases in annealing temperatures caused the ions to outdiffuse and intermix with YBCO. In contrast, nickel ions do not show gettering effect, rather they outdiffuse after annealing. The crystal damage caused by the implantation and chemical reaction between implanted ions and target material seemed to be the main reason of this gettering effect. [ABSTRACT FROM PUBLISHER]