Comparison of microstructure (MS), initial electroluminescence (EL) and photoluminescence (PL) images with the strength of LETID effect (detected by EL) from the same location in mc-Si solar cell fabricated in PERC technology. Note the close correspondence of LETID effect with MS and PL and a much worse correlation between MS and EL. In the study, we used EL, PL methods together with capacitance-voltage (CV) and deep-level transient spectroscopy (DLTS) technique to get insight into the roots of LETID. More details can be found in article number 1800918 by Teimuraz Mchedlidze, Joerg Weber, and co-workers.

Industrial bifacial PERC solar cells show a new type of potential induced degradation (PID) at the rear side. After PID stress, cells exhibit power losses about 12 %_rel. The origin of the losses is traced back to a local silicon corrosion, forming hole shaped damages within the passivation layers at the rear side. More details can be found in article number 1900334 by Kai Sporleder, Christian Hagendorf, and co-workers.

To improve the performance of CMOS image sensors, the authors currently develop a cyanide-related multielement molecular (CH₄N) ion-implanted epitaxial Si wafer. The CH₄N ion-implanted epitaxial Si wafer has two kinds of defects; C agglomeration defects and stacking faults. These defects contribute to high metal gettering capability and retention capability for H, C, and N. More details can be found in article number 1900172 by Akihiro Suzuki, Kazunari Kurita, and co-workers.

Transition metals strongly impact the electrical device performance, i.e., carrier lifetime, leakage current, low-frequency noise, photocurrent, and solar cell efficiency. CMOS image sensors (CIS) and solar cells are also degraded by metal contamination. Density functional theory (DFT) ab initio calculations are frequently used to get a deeper physical insight in the defect structure. These different aspects are briefly reviewed.

Experimental results on the electronic and dynamic properties of a defect consisting of a substitutional boron atom and an oxygen dimer (B_sO₂) in silicon are presented. It is shown that the B_sO₂ complex is a defect with negative-U properties, and it is responsible for persistent photoconductivity and light-induced degradation of efficiency of solar cells produced from Si:B+O crystals.

This article reports on the characterization of defects limiting n-type multicrystalline silicon solar cells. Both defect identification and quantitative assessment of the defects' impact on cell performance are addressed. A higher tolerance against common metallic point defects is found. Material limitation becomes evident at decorated structural defects, such as dislocation clusters and grain boundaries.

Bifacial passivated emitter and rear cells (PERC+) can suffer from a potential-induced degradation (PID) at the rear side. A microstructural analysis shows localized spots with increased carrier recombination as the origin of the power losses. A corrosion of the silicon bulk at the silicon/aluminium oxide interface is the root cause of the degradation.

In mc-Si solar cells degraded at elevated temperatures under carrier injection (CeTID, LeTID), the degree of local degradation correlates with the local concentration of minority traps activated during the degradation, with local doping level and local density of structural defects.

SiGe and a-Si/SiGe surfaces are sonochemically treated in chloroform (CHCl₃) to improve the photovoltaic performance. The photovoltage magnitude and decay time can increase up to 50%. It is proposed that reactive Si dangling bonds revealed on the surfaces are saturated by the hydrocarbon species decomposed from CHCl₃. This surface passivation can be promising for improving SiGe-based photovoltaic materials.

A low-cost technology is presented for the realization of high breakdown voltages in power electronics that allows the deep diffusion of aluminum from a physically deposited source. The approach requires only standard process steps that are already established in the manufacturing of silicon power devices. A full numerical analysis of the resulting profiles is provided.

Silicon high voltage p+/n− diodes are intentionally doped with platinum for minority carrier lifetime adjustment. However, platinum–hydrogen (Pt–H) defects are formed during processing, which are degrading the reverse characteristics of these diodes. Therefore, the annealing of these defects is investigated via deep-level transient spectroscopy (DLTS) and modeled via a first-order dissociation reaction.

To reveal the gettering mechanism of copper, the dependence of gettering efficiency and copper precipitation on dopant concentration is investigated using n-type silicon wafers. Copper precipitates below a dopant concentration of 10¹⁹ cm⁻³, while no copper precipitates above 10¹⁹ cm⁻³ although strong gettering occurs, suggesting that the gettering mechanism changes from relaxation to segregation with increasing dopant concentration.

The use of 300 mm silicon wafers strongly increases the productivity of a manufacturing line for insulated gate bipolar transistors. However, 300 mm float-zone silicon is not available, so that the Czochralski material is required. For this, several critical issues have to be solved: crystal originated particles, the axial-doping variation along the crystal, and the minimization of the concentration of C_IO_IH complexes.

The impact of in situ annealing on the electrical properties of AlN/(111) p-type silicon metal–insulator–semiconductor (MIS) capacitors is studied by capacitance–voltage (C–V) and deep-level transient spectroscopy (DLTS). It is demonstrated that the in-diffusion of Al leads to an enhanced free hole concentration close to the interface and the presence of near mid-gap hole traps. The trap parameters are modified by the annealing treatment.

Behavior of iron–boron (FeB) pairs in boron-doped Czochralski silicon after extended gettering by phosphorus implantation at different temperatures is studied. The kinetic parameters of the light-induced dissociation of iron–boron pairs under standardized illumination, i.e., 1 and 0.5 sun, as well as the characteristics of their formation in the dark, are determined.

The anisotropy A_pe of the photo-elastic constant is reviewed in experiments and simulations for single-crystalline silicon. (100) Si wafers are diametrically loaded in different crystallographic orientations and studied by means of the plane polariscope scanning infrared depolarization (SIRD) imager. A_pe introduced as the ratio of the piezo-optical coefficients (π₁₁ − π₁₂ − π₄₄)/(π₁₁ − π₁₂ + π₄₄) is determined to be (0.21 ± 0.01).

Excellent passivation of silicon surfaces is achieved via optimization of an iodine–ethanol (I–E) scheme. A robust method based on samples with different thicknesses cut from the same float-zone ingot is used to determine a lowest surface recombination velocity of 4.4 cm s⁻¹ for (100)-orientation silicon. I–E is demonstrated to be superior to superacid-derived passivation for (111)-orientation silicon surfaces.

The oxygen precipitation in the as-grown defect-free region of nitrogen-doped Czochralski silicon single crystals with low oxygen concentrations ([Oi]) is investigated. Oxide precipitates are completely suppressed at an [Oi] value below 3 × 10¹⁷ atoms cm⁻³. A thermodynamic model for oxygen precipitation indicates that the growth onset temperature of embryos is extremely low to grow as stable oxide precipitates.

The composition of the boron–oxygen-related light-induced degradation (BO-LID) defect is an unresolved issue. Recently, BO-LID is suggested to be due to the A_Si-Si_i-defect. Thus, creation and discreation of BO-LID is governed by the interstitial silicon concentration. Annealing and electron beam irradiation are applied. BO-LID is created in oxygenated silicon after 4 h annealing at 650 °C and discreated by 16 h annealing at 1050 °C.

Experimental observations and quantum mechanical device simulations point to different electronic properties of the dislocations in Si and Ge. A supermetallic conduction behavior and strain-induced carrier confinement (1D electron gas) are proved for dislocations in Si. Both are not confirmed for Ge. The carrier confinement results in higher electron concentrations on dislocation cores in Si than on dislocations in Ge.

The behavior of the nonequilibrium charge carrier lifetime in Czochralski-grown n-Si after irradiation and subsequent annealing (20–380 °C) are investigated. It is shown that change in lifetime in the annealing range of 180–380 °C is caused by the divacancy-oxygen (V₂O) complexes. The values of hole capture cross-section and the parameters of V₂O formation and annealing are determined.

The electronic transition at 4296.8 cm^–1 is revealed in the absorption spectra of boron-doped Si irradiated at 80 K with 5 MeV electrons. The disappearance of the defect responsible for the registered line upon annealing is accompanied by the emergence of the B_iB_s complex. The found defect is identified as a precursor of a stable configuration of B_iB_s.

Two types of stacking faults (SFs) in InGaAs are observed by electron channeling contrast imaging (ECCI). By comparing their shapes and invisibility conditions, Frank SFs, followed by a Lomer–Cottrell lock and glissile SFs with two Shockley partial dislocations, can be distinguished. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) are also performed to validate the results in this study.

Grain structures and electrical properties are studied in silicon contaminated with impurities. The presence of carbon induces a higher amount of grain nucleation, resulting in the high-order twin and random angle grain boundaries. Cu can lead to solid–liquid interface destabilization. Lifetime maps demonstrate the influence of impurities on the electrical activity in relation to the crystallographic defects and grains.

Heating of silicon with high oxygen concentrations at around 450 °C generates thermal double donors (TDD). The energy levels up to 17 donors are very similar, which makes it impossible to separate the single species by deep level transient spectroscopy (DLTS) measurements. Using high-resolution Laplace DLTS, the first three TDDs are resolved, and their properties are determined.

Polarization dependence of dislocation-related luminescence (DRL) from a-screw dislocations introduced by local plastic deformation in n-GaN is found to be different for two components of DRL spectral doublet: the high-energy component is polarized parallel, whereas the low-energy component is inclined under the angle of about 40° to the dislocation line.

Transmission electron microscopy (TEM) investigations show that dopant-oxide stacks such as P₂O₅/Sb₂O₅ and B₂O₃/Sb₂O₅ grown by atomic layer deposition (ALD) on silicon transfer during annealing to silicon oxide with embedded spherical, partially crystalline particles. Dopant diffusion from these layers leads to shallow profiles with high phosphorus (>1 × 10²⁰ cm⁻³) and boron (>1 × 10²¹ cm⁻³) concentrations in silicon. A numerical analysis of the diffusion process is provided.

The influence of millisecond flash lamp annealing (FLA) on epitaxial, defect-enhanced quantum dot (DEQD) light emitters is investigated, demonstrating the thermal robustness of these group-IV nanostructures and improved light emission yield over a large range of temperatures.

In situ heating transmission electron microscopy (TEM) possesses even stronger requirements on sample preparation than conventional TEM. Therefore, this article presents novel methods for tackling this issue. Using the example of Al-Si alloying at grain boundaries, the capabilities of the methods to produce low contamination, site-specific lamellas from ion beam sensitive samples are examined.

Passivation of detector-grade float-zone (FZ) silicon with aluminum oxide (Al₂O₃) is studied, focusing on the effect of post-annealing temperature on carrier lifetimes and film properties. It is confirmed that Al₂O₃ provides excellent surface passivation on high-resistivity FZ-Si substrates. Bulk lifetime degradation during low-temperature annealing can be prevented by high-temperature treatment only in p-type substrates.

Oxidation processes under different conditions can lead to the formation of electrically active defects in silicon wafers. A significant degradation of minority carrier diffusion length is observed in wet oxidized p-type silicon wafers by using the surface photovoltage technique. Such a degradation is not detected in wet oxidized n-type silicon wafers. Different models are suggested to explain this degradation.

Cu is introduced into n-type Si at room temperature from a polishing slurry. Interstitial Cu is shown to create new defects with a substitutional Pt. The electrical parameters of the defects are determined and tentatively identied with complexes of one substitutional Pt atom and n = 1 to 4 interstitial Cu atoms (Pt_S (Cu_i)_n).

Radiation damage in 4H-SiC produced by 1.05–10 MeV electrons is investigated by deep-level transient spectroscopy. Introduced damage is very similar in the whole energy spectrum; however, with increasing energy, the number of simple defects saturates, and the amount of defect clusters grows. The carrier removal rate caused by the introduced acceptor centers follows well the classical nonionization energy loss scaling.

The measured etch pit density in mc-Si material is shown to be reduced by P-gettering. Various pieces of evidence are presented, suggesting that defect etching does not reveal impurity-lean dislocations.

The temperature field across a Czochralski throughout crystallization is a key quantity governing process (energy uptake) or material (thermal stress, defects) parameters. It is typically derived using simulations and hard to confirm experimentally. A post-growth method is proposed to validate calculated temperature field evolution, based on the measurement of thermal donors, a relic of the ingot thermal history.

The preparation of c-Si nanowires and porous nanolayers using the two-stage metal-assisted chemical etching process is studied. The structures are characterized in all stages of the process by spectroscopic ellipsometry and using the following two approaches: 1) with the complex pseudo-dielectric function determined and analyzed and 2) with parameters of simulated multilayer structures determined in the effective medium approximation.

Herein, a multi-stage defect-engineering approach is developed, incorporating gettering and hydrogenation to improve the quality of low-cost silicon wafers. This technique is applied to p-type upgraded metallurgical-grade multicrystalline silicon wafers from the edge of the silicon cast. Silicon heterojunction solar cells are fabricated with these defect-engineered wafers, achieving an impressive open circuit of >690 mV and efficiency of 18.7%.

The effective carrier lifetime (at an excess carrier density of 7 × 10¹⁵ cm⁻³) of the as-cut and as-treated samples, which are extracted from five locations (from bottom to top) of a high-performance multicrystalline silicon ingot, are characterized. The substantial lifetime improvements highlight the strong external gettering effect achieved by both p-type and n-type poly-Si passivating contact fabrication processes.

The specific impact of different defect species in crystalline silicon on the injection-dependent excess carrier lifetime is used to identify defect species and analyze their properties. Especially, the lifetime-equivalent defect density as a measure of the actual defect density helps to distinguish different defect species encountered during light-induced degradation phenomena.

The temperature dependence of dislocation-related photoluminescence in silicon samples with dislocations created by self-ion implantation with subsequent annealing and additional boron doping, is investigated. Aluminum gettering and identical heat treatments make it possible to significantly improve luminescence temperature dependence and ensure the maintenance of dislocation-related luminescence up to 270 K. The observed effect is clearly associated with boron doping.

A simulation model for dissolution of octahedral bulk micro defects (BMD) in pure argon or oxidizing ambient is developed. The model is capable of predicting under which rapid thermal annealing (RTA) conditions the BMD nuclei dissolution occurs. In addition, the impact of the RTA process sequence on the homogeneity of the BMD-denuded zone is evaluated.

The deep-level transient spectroscopy (DLTS) technique is used to study the room-temperature interaction of the extended defects introduced in Si by plastic deformation with the mobile Ni species. A special deformation geometry enables to separate contributions from the dislocations and the dislocation trails. It is shown that Ni decorates the extended defects, increasing the concentration of deep-level centers by an order of magnitude.

Embedded positive charge of oxygen precipitates (OPs) formed by thermal treatment of oxygen-implanted silicon decreases inversely proportional to their size, giving evidence of the charge localization in thin nonstoichiometric shell of OPs. The treatment at 700 °C results in the formation of nanosized defects and in an inhomogeneous electric structure of the oxygen-implanted region.

The majority of electronically active defects in SiC are located deep within the bandgap, thereby degrading the carrier transport properties of SiC. This study compares the diffusion of a carbon vacancy in different (0001)-layers relative to a SiO₂/SiC interface using the density-functional theory simulations. The results show that vacancies in the upper layers are stabilized due to stronger bonding and interfacial relaxation.

The influence of the injection of minority charge carriers on the formation of a divalent bistable defect (DBH) is investigated. The production of such bistable defect is enhanced in materials with a high ratio of boron to carbon concentrations. It is concluded that the DBH defect has inverse occupancy level ordering in its stable configuration.