Defect Characterization Methods Research Articles

Correction: Image-Based Fracture Surface Defect Characterization Methods for Additively Manufactured Ti-6Al-4V Tested in Fatigue

Correction: Image-Based Fracture Surface Defect Characterization Methods for Additively Manufactured Ti-6Al-4V Tested in Fatigue

A three-directional stress-strain model-based physics-embedded prediction framework for metal tube full-bent cross-sectional characteristics

A metal tube system is known as the industrial blood vessel, among which the bent section is the most vulnerable part. The cross-sectional defects (CSDs) of the bent tube cause the flow fluctuation of the fluid inside the tube. The existing defect characterization methods are roughly presented by describing CSDs in some specific cross-sections, which results in the lack of the tube full-bent section (FBS) characteristic information. To comprehensively describe and predict the tube FBS characteristics, an advanced physics-embedded CSDs prediction framework is proposed. This framework includes an FBS-neutral layer displacement angle (NLDA) prediction module and an FBS-CSDs prediction module, which uses the method that integrates the analytical model and BiLSTM-based deep learning (DL) models to predict the CSDs in the FBS of the tube. A novel analytical model of CSDs that considers both three-directional stresses and strains during tube bending is embedded in the FBS-CSDs prediction module. The analytical model provides the initial predicted values of CSDs through the NLDA sequence obtained from the FBS-NLDA module. The inaccurate CSDs are then treated as physical information to be fed into DL models for further correction and prediction. The prediction performance of this framework is validated through numerical simulations and experiments. The results prove that the framework can accurately predict the CSDs in the tube FBS. The integration of DL models with the analytical model not only overcomes the limitations of the analytical model, but also improves the prediction accuracy and convergence speed of DL models.

Image-Based Fracture Surface Defect Characterization Methods for Additively Manufactured Ti-6Al-4V Tested in Fatigue

Fatigue initiation in additively manufactured samples/parts often occurs at processed-induced defects such as lack-of-fusion (LoF), keyhole, or other morphological/microstructural defects that have unique characteristics and measurable qualities. Attempts at identifying and minimizing such defects have utilized optimized processing conditions along with in situ and ex situ characterization that includes metallography and/or X-ray computed tomography (XCT). This paper highlights the benefits of using fracture surface analyses to detect and quantify defects that may not be detected by metallography/XCT due to sectioning and resolution limits. In addition to using manual quantification of fatigue initiating LoF and keyhole defects on fracture surfaces, image-based machine learning using convolutional neural networks such as U-Net were also used to automate the process. Statistical analyses were used to identify the extreme cases of defects that initiated and accelerated fatigue and to model the distribution of defect size and shape characteristics to distinguish the type of defect. Initial results show agreement between trained machine learning models and ground truth data in defect segmentation, and the distributions of defect characteristics are distinguishable to particular process-induced defect types.

Progress in Gallium Oxide Field-Effect Transistors for High-Power and RF Applications.

Power electronics are becoming increasingly more important, as electrical energy constitutes 40% of the total primary energy usage in the USA and is expected to grow rapidly with the emergence of electric vehicles, renewable energy generation, and energy storage. New materials that are better suited for high-power applications are needed as the Si material limit is reached. Beta-phase gallium oxide (β-Ga2O3) is a promising ultra-wide-bandgap (UWBG) semiconductor for high-power and RF electronics due to its bandgap of 4.9 eV, large theoretical breakdown electric field of 8 MV cm-1, and Baliga figure of merit of 3300, 3-10 times larger than that of SiC and GaN. Moreover, β-Ga2O3 is the only WBG material that can be grown from melt, making large, high-quality, dopable substrates at low costs feasible. Significant efforts in the high-quality epitaxial growth of β-Ga2O3 and β-(AlxGa1-x)2O3 heterostructures has led to high-performance devices for high-power and RF applications. In this report, we provide a comprehensive summary of the progress in β-Ga2O3 field-effect transistors (FETs) including a variety of transistor designs, channel materials, ohmic contact formations and improvements, gate dielectrics, and fabrication processes. Additionally, novel structures proposed through simulations and not yet realized in β-Ga2O3 are presented. Main issues such as defect characterization methods and relevant material preparation, thermal studies and management, and the lack of p-type doping with investigated alternatives are also discussed. Finally, major strategies and outlooks for commercial use will be outlined.

Study on annealing effect of bipolar transistors at different temperatures after total dose irradiation

The article investigates the annealing process of bipolar transistors after total dose irradiation, using the GLPNP transistor as the research object. After total dose irradiation, room temperature and high temperature annealing tests were carried out. Gummel curve, GS curve and SS curve of bipolar transistor are obtained by I/V scanning, gate scanning and sub-threshold scanning. The evolution behavior of radiation-induced oxide trap charges and interface state damage defects during annealing of bipolar transistors at different temperatures was quantitatively analyzed by different microscopic defect characterization methods. Generally speaking, this study is of great significance to better understand the recovery mechanism of electrical properties of bipolar transistors during annealing after total dose irradiation, and can provide reference for the design, application and radiation-hard of transistors.

Detection and Characterization of Defects in Additive Manufacturing by Polarization-Based Imaging System

Additive manufacturing (AM) technology such as selective laser melting (SLM) often produces a high reflection phenomenon that makes defect detection and information extraction challenging. Meanwhile, it is essential to establish a characterization method for defect analysis to provide sufficient information for process diagnosis and optimization. However, there is still a lack of universal standards for the characterization of defects in SLM parts. In this study, a polarization-based imaging system was proposed, and a set of characterization parameters for SLM defects was established. The contrast, defect contour information, and high reflection suppression effect of the SLM part defects were analyzed. Comparative analysis was conducted on defect characterization parameters, including geometric and texture parameters. The experimental results demonstrated the effects of the polarization imaging system and verified the feasibility of the defect feature extraction and characterization method. The research work provides an effective solution for defect detection and helps to establish a universal standard for defect characterization in additive manufacturing.

Defect Characterization Method for Bridge Cables Based on Topology of Dynamical Reconstruction of Magnetostrictive Guided Wave Testing Signals

Defect Characterization Method for Bridge Cables Based on Topology of Dynamical Reconstruction of Magnetostrictive Guided Wave Testing Signals

Localised corrosion failure of an L245N pipeline in a CO2–O2–Cl− environment

ABSTRACT Multicomponent thermal fluid flooding has become a widely used and very effective heavy-oil recovery technology, but the harsh CO2–O2–Cl− environment can lead to serious corrosion perforation failure of the pipeline. Therefore, the influence of O2 content and main controlling factors on corrosion perforation were investigated through a weight-loss experiment, corrosion defect test, characterization and grey correlation method. The results showed that, with the increase in O2 content, the general corrosion rate and localized corrosion rate increased. The uneven protection performance of the product after the addition of O2 was found to be the key cause of localized corrosion. In addition, the synergistic effect of O2–Cl− promoted the lateral and longitudinal expansion of pits. The results of the grey correlation showed that the temperature (30–120 °C) had a greater impact on localized corrosion compared with the content of O2 (0–0.045 MPa) and Cl− (0–16,000 mg/L).

Bulk defect characterization in metalized solar cells using temperature-dependent Suns-Voc measurements

Extracting the parameters, energy level and electron-to-hole capture cross-section ratio, of efficiency-limiting bulk defects in silicon solar cells is a critical step in identifying those defects and potentially eliminating their impact. Typically, this is achieved on specially prepared test structures. However, in some cases, this is not possible, especially in mass production lines when only completed solar cells are available. In this study, a method that is based on temperature-dependent Suns-V oc measurements is introduced to extract the defect parameters in metalized solar cells. The method is validated by comparing the parameters of the boron-oxygen-related defect extracted from cells and those extracted from wafers using the commonly used temperature- and injection-dependent lifetime spectroscopy. It is shown that this method has the benefit of a more accurate lifetime at low injection levels compared with photoconductance-based lifetime measurement since it is not impacted by minority carrier traps. The proposed technique is then applied to determine the parameters of the defect causing light-induced degradation in gallium-doped silicon solar cells. We determined an energy level, with respect to the intrinsic level, of −0.26 ± 0.04 eV and a capture cross-section ratio of 34 ± 2 for this defect. Finally, a sensitivity analysis is performed by considering the system’s limited measurement temperature range. The findings demonstrate the potential of the temperature-dependent Suns-V oc method as a fast and easy-to-apply method for defect characterization in metalized cells. • Parameters of bulk defects in cells can be extracted using Sun-V oc (T) method. • The method is validated by extracting the parameters of BO-related defects. • The parameters of LID-related defects in Ga-doped cells are extracted with the method. • Sensitivity analysis is performed to assess the limitations of the method.

Atomic-level defect modulation and characterization methods in 2D materials

Two-dimensional (2D) materials are attracting increasing research interest owing to their distinct tunable physical properties. Moreover, the ubiquitous defects in 2D materials offer an opportunity to tailor their electronic properties. Recently, atomic-level structural modification methods for 2D materials have been developed, further triggering the need for the precise control of defects. Following the ground-breaking advancements in the atomic-scale characterization of defects in 2D materials, valuable information on defect-driven electronic properties has been published. It is therefore important to present a review work on the recent research developments on atomic-level defect control and characterization of 2D materials. This Perspective highlights the type and role of atomic defects in 2D materials, as well as some current technologies for engineering such defects. In addition, we emphasize on atomic-level characterization methods with a focus on aberration-corrected transmission electron microscopy and deep learning as a powerful method for characterizing defects in 2D materials. Based on the two characterization techniques, we present the experimental results of laser-induced structurally modified MoTe2 and transition metal decorated h-BN. We believe that this work will provide fundamental knowledge for engineering and characterizing defects in 2D materials for the design of application-specific electronic devices.

(Invited) Detection of Dislocations Using X-Ray Diffraction Imaging (Topography) KOH Etching and Their Evolution after Epitaxial Growth in 4H-SiC

This work reports the characterization and analysis of various types of SiC substrate wafers by a high throughput (2 wafers/hour) X-ray diffraction imaging (XRDI) system. Quantitative maps of various dislocations are obtained using Automated Defect Classification (ADC) and correlated to other defect characterization methods including molten KOH etching and Photoluminescence (PL) scans. Different and often complementary views of the wafer were obtained by integrating the data. Epitaxial layers grown on the substrates show the probabilistic pattern of nucleation for various types of extended defects from defects in the underlying crystal structure. Nucleated Stacking Faults, especially, were well correlated with distributions of Basal Plane dislocations in the substrates.

Quantum Sensor for Nanoscale Defect Characterization

The optical and electronic properties of semiconductors are strongly affected by structural and stoichiometric defects. The precise incorporation of dopants and the control of impurities are essentially what makes semiconductors useful materials for a broad range of devices. The standard defect and impurity characterization methods are sensitive only on a macroscopic scale, like the most widely used method of deep-level transient spectroscopy (DLTS). We perform time-resolved measurements of the resonance fluorescence of a single self-assembled $(\mathrm{In},\mathrm{Ga})$$\mathrm{As}$ quantum dot (QD) at low temperatures ($4.2\phantom{\rule{0.2em}{0ex}}\mathrm{K}$). By pulsing the applied gate voltage, we are able to selectively occupy and unoccupy individual defects in the vicinity of the dot. We address the exciton transition of the QD with a tunable diode laser. Our time-resolved measurements exhibit a shift of the resonance energy of the optical transition. We attribute this to a change of the electric field in the dot's vicinity, caused by electrons tunneling from a reservoir to the defect sites. Furthermore, we are able to characterize the defects concerning their position and activation energy by modeling our experimental data. Our results thus demonstrate how a quantum dot can be used as a quantum sensor to characterize the position and activation energy of individual shallow defects on the nanoscale.

Review on Defect Characterization and Structural Integrity Assessment Method of Additively Manufactured Materials

Review on Defect Characterization and Structural Integrity Assessment Method of Additively Manufactured Materials

Defect spectroscopy on the dielectric material aluminum oxide

A method for defect characterization is presented that allows to measure the activation energy, capture cross-section, and defect density in dielectric materials. This is exemplarily performed on aluminum oxide thin films deposited on hydrogen-terminated diamond. During the measurement, samples were illuminated using a 405 nm laser, charging the defects while simultaneously measuring the surface conductivity of the diamond at different temperatures. By applying the standard boxcar evaluation known from deep-level transient spectroscopy, we found five different defect levels in hbox {Al}_2hbox {O}_3. One can be identified as substitutional silicon in aluminum oxide, while the others are most likely connected to either aluminum interstitials or carbon and nitrogen impurities.

Electronic transport characterization of B+ ion-implanted silicon wafers with nonlinear photocarrier radiometry

A nonlinear photocarrier radiometry (PCR) based quantitative defect characterization method is applied to determine the electronic transport parameters of the implantation layer of B+ ion-implanted silicon wafers with different implantation doses. A rigorous two-layer nonlinear PCR model is employed to fit the experimental modulation frequency dependences of PCR amplitude and phase to determine the transport parameters, that is, the carrier lifetime, carrier diffusion coefficient, and front surface recombination velocity of the implantation layer via multiparameter fitting. In the multiparameter fitting, the effects of the implantation layer thickness determination on the extraction of the electronic transport properties of the implantation layer are discussed via setting the thickness as a free parameter in the multiparameter fitting and fixed parameters determined by Monte Carlo based TRIM calculation. The fitted implantation layer thicknesses are in good agreement with that determined via TRIM calculation with a modified electronic damage threshold. Monotonic dependences of the transport properties of the implantation layers on the implantation dose are observed, and the effects of impurity density on the transport properties of the implantation layers are discussed. Good agreements between the experimental implantation dose dependence of the nonlinearity coefficient and corresponding theoretical calculations with the determined transport parameters are obtained. These results show that the two-layer nonlinear PCR model is accurate for quantitatively characterizing the transport properties and thickness of the ion-implantation layers of silicon wafers, and the nonlinear PCR technique is appropriate for precise defect characterization in the semiconductor manufacturing processes.

The effects of the global surface curvature on Makyoh-topogaphy imaging

The effects of the global curvature of the reflecting surface on Makyoh (magic-mirror) topography imaging is analysed based on a geometrical optical model. It is shown that the effects can be taken into account by introducing an equivalent screen-to-sample distance which is a function of the real screen-to-sample distance and the global curvature. The special limiting cases are discussed and analysed for practical applications. Full Text: PDF ReferencesK. Kugimiya, "“Makyoh”: The 2000 year old technology still alive", J. Cryst. Growth 103, 420 (1990). CrossRef P. Blaustein, S. Hahn, "Realtime inspection of wafer surfaces", Solid State Technol. 32, 27 (1989). CrossRef Z.J. Pei, G.R. Fisher, M. Bhagavat, S. Kassir, "A grinding-based manufacturing method for silicon wafers: an experimental investigation", Int. J. Machine Tools Manufacture 45, 1140 (2005). CrossRef F. Riesz, "Makyoh topography: a simple yet powerful optical method for flatness and defect characterization of mirror-like surfaces", Proc. SPIE 5458, 86 (2004). CrossRef T. Hirogaki, E. Aoyama, R. Machinaka, H. Sueda, K. Ogawa, J. Japan Soc. Precision Eng. 73, 96 (2007). CrossRef G. Saines, M.G. Tomilin, "Magic mirrors of the Orient", J. Opt. Technol. 66, 758 (1999). CrossRef W.E. Ayrton, J. Perry, "The Magic Mirror of Japan. Part I", Proc. Roy. Soc. London 28, 127 (1878). CrossRef M.V. Berry, "Oriental magic mirrors and the Laplacian image", Eur. J. Phys. 27, 109 (2006). CrossRef F. Riesz, "Sensitivity and detectability in Makyoh imaging", Optik 122, 2115 (2011). CrossRef Z.J. Laczik, "Quantitative Makyoh topography", Opt. Eng. 39, 2562 (2000). CrossRef F. Riesz, "Geometrical optical model of the image formation in Makyoh (magic-mirror) topography", J. Phys. D: Appl. Phys. 33, 3033 (2000). CrossRef F. Riesz, "Camera length and field of view in Makyoh-topography instruments", Rev. Sci. Instr. 72, 1591 (2001). CrossRef J. Szabó, F. Riesz, B. Szentpáli, "Makyoh Topography: Curvature Measurements and Implications for the Image Formation", Japan. J. Appl. Phys. 35, L258 (1996). CrossRef F. Riesz, "Non-linearity and related features of Makyoh (magic-mirror) imaging", J. Opt. 15, 075709 (2013). CrossRef A.V. Gitin, "System approach to image formation in a magic mirror", Appl. Opt. 48, 1268 (2009). CrossRef

Defect Characterization in Organic Semiconductors by Forward Bias Capacitance–Voltage (FB-CV) Analysis

Transport in organic semiconductors (OSCs) generally is poorer relative to their inorganic counterparts, mainly due to the high defect density that trap the free charge carriers. In this article, we demonstrate a new defect characterization method based on forward bias capacitance–voltage (FB-CV) measurements, which is appropriate for a broad range of low mobility OSCs with relatively large (>1.5 eV) band gaps. The characterization method, developed using numerical modeling and experimental data, relates the capacitance peaks in the FB-CV sweep to the deep level defect states; these states are inaccessible to classical reverse bias (RB) impedance spectroscopy. We validate the proposed technique by interpreting FB-CV data for organic photodiodes made of a commonly used semiconducting polymers, poly(3-hexylthiophene) (P3HT), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), and copper(II) phthalocyanine (CuPc). We find that P3HT and MEH-PPV contain both shallow and deep level states, but ...

Thin-film Silicon Solar Cell and Module Analysis by Electroluminescence

Electroluminescence is a fast and reliable method for defect characterization of thin-film silicon large area modules. At forward bias, the injected carriers recombine via defect states in the p-i-n structure but only the radiating portion is detected by a means of a detector array. For these investigations, it is mainly assumed that the EL-signal is proportional to the local current density (J). We will present a detailed analysis of thin-film silicon modules and the circumstances will be discussed under which the simple approach with the EL-signal proportional to the current density is not valid.

Novel Coupled Electric Field Method for Defect Characterization in Eddy Current Non-destructive Testing Systems

This article presents a defect modeling in eddy current non-destructive testing systems by using a new developed method called coupled electric field. It permits to improve qualitatively several models developed so far by many authors using coupled circuit methods that consider the defect only as loss of material. However, a defect can occur with a finite conductivity such as impurity, small burns and micro-solder. For this reason, this investigation consists of extending the coupled circuit method to the modeling of this kind of defects. The proposed approach consists of firstly considering the defect as an electric conductive volume and secondly changing the state variable presenting the electric current by the electric field one. This procedure permits expressing explicitly the impedance variation caused by the presence of an axi-symmetrical defect according to its characteristics. The comparison between the impedance variations calculated using finite elements method and the proposed one demonstrates a very good concordance. After this validation, the study covers also the influence of the defect shape and position on encircling probe impedance. This method is interesting since it permits a fully characterization of this kind of defects and facilitates the inversion process. Moreover, using a 3D finite element observation, this fast tool of simulation can be adapted for a fast phenomenological modeling of asymmetrical configurations.

Back Cover: Defect generation, advanced crystallization, and characterization methods for high‐quality solar‐cell silicon (Phys. Status Solidi A 4/2013)

Back Cover: Defect generation, advanced crystallization, and characterization methods for high‐quality solar‐cell silicon (Phys. Status Solidi A 4/2013)