Papers by Keyword: Screening

Abstract: This study demonstrates a negative correlation between gate leakage current () and time to breakdown () of gate oxide in various commercial SiC discrete MOSFETs and power modules. SiC MOSFETs with higher leakage current at the same gate voltage exhibit lower oxide failure time in the constant-voltage Time-Dependent Dielectric Breakdown (TDDB) test. The novelty lies in the discovery that measured under conditions of either low gate voltage () at RT or high at 150°C can be utilized to identify discrete devices or power modules with non-infant failures or lower intrinsic lifetime. Aggressive screening based on helps to reduce non-infant extrinsic failure probability and identify devices with more uniformity of intrinsic lifetime.

Abstract: The reliability issue of the bipolar degradation in 4H-SiC devices has not been completely eliminated. We have been proposing a screening method for latent defects causing this reliability issue utilizing UV irradiation, which we call the E-V-C (Expansion-Visualization-Contraction) method. This method is based on the property that the REDG (recombination-enhanced dislocation glide) mechanism that causes the bipolar degradation can be reproduced by UV irradiation. However, in order to apply this method as a screening method, accurate quantification of the correlation between current density in forward bias and UV irradiance is required. In this article, we estimated the extent to which the carrier lifetime of the sample affects the quantification of the correlation and found that it had a non-negligible degree of influence on the correlation. Then, we tried to find if there is a simple method for estimating carrier lifetime that can be incorporated in the screening process, and report on our attempts in progress.

Abstract: We have proposed an E-V-C (Expansion-Visualization-Contraction) method by using UV irradiation, for screening potential defects which causes reliability issue called bipolar degradation in 4H-SiC devices. This method is based on the property that the REDG (recombination-enhanced dislocation glide) mechanism causing the bipolar degradation can be reproduced by UV irradiation. However, in order to apply this method as a screening, accurate quantification of the correlation between current density in forward bias and UV irradiance is required. This article describes how to set UV irradiation conditions (irradiance and irradiation time) to simulate forward biased current conditions.

Abstract: In 4H-SiC devices, the reliability issue of the bipolar degradation, which is caused by the nucleation and expansion of 1SSF (single Shockley stacking fault) defects originating from basal plane dislocations (BPDs), has not been completely eliminated. To avoid the reliability issue, in some device manufacturers is currently introduced so-called "burn-in" (accelerated current stress) screening operation, which is very time-consuming process which raises a total cost of production. While, the bipolar degradation is explained by the REDG (recombination-enhanced dislocation glide) mechanism, and the same degradation can be induced by UV (ultraviolet) irradiation. Using this property, we have been proposing a new screening method to detect latent defects with expanding to 1SSFs at an early stage of manufacturing. In order to bring this screening method to a practical level, it is essential to correlate the accelerated current stress with the UV irradiation quantitatively in terms of the effect of 1SSF expansion. We have attained some progress in an attempt to quantify this correlation and describe it in this paper.

Abstract: We are currently developing an inspection system that will provide a low-cost means of screening prior to shipment by fully visualizing latent 1SSF (single Shockley stacking fault) defects originating from basal plane dislocations (BPDs) that cannot be detected by current defect inspection systems. The system will capture not only the defects that expand into right triangles under relatively low-level forward bias, but also the defects that expand into more serious bar-shaped 1SSFs under relatively high-level forward bias, with a particular focus on capturing TED (threading edge dislocation)-converted BPD at or below the buffer layer/substrate interface. Since these defects are known to cause forward voltage degradation during device operation, so-called "burn-in" (accelerated current stress) screening operation is currently utilized in some device manufacturers to avoid the shipping of the defective devices, but it is very time-consuming process which raises a total cost of production. The system we are developing, which can significantly reduce the screening time, has the potential to replace the "burn-in" operation.

Abstract: The objective of a project is to make an integrated technological solution to assist and help companies in their hiring process. We have come up with the concept for prioritization of candidates using automated behavioural interview. This is a web-based portal that will be supporting the recruitment operations by prioritizing candidates from a large pool of candidates based on skills and experiences relevant to the job. Facilitating an informed interview process for a candidate with systematic transparent procedure. Our project aims to apply our technical skills to facilitate interviewers and address the challenges faced by the organization in its hiring process. This has been addressed using recording the answers of random behavioural questions with limited time to prepare, then video will be analysed to find the behavioural aspect of the candidate. Behavioural analysis of the interview is done by applying facial emotion recognition based on VGG Net Architecture.

Abstract: The statistical model is created for predicting penetration depth in an alternating current-based additional axial magnetic field controlled shielded metal arc welding of ASTM A 516 Gr.70 steel. The design for the trials is developed using the Placket-Burman design and response surface methodology. The created model determines the optimum process variables for getting excellent penetration depth. The input variables (current, magnetic field density, and magnetic frequency) are chosen for a response like penetration depth. This model can predict the main effects and the interacting effects of three process variables. The findings reveal that a higher current value with a low magnetic field density leads to deeper penetration and vice versa. Furthermore, a greater penetration depth is achieved at lower magnetic field density and higher magnetic frequency. With a desirability of 98.8%, the optimum process variables are 110 A, 0 mT, and 60 Hz. The predicted response values produced from the regression equation based upon process variables are extremely similar to the observed output, demonstrating the usefulness of second-order regression equations. For improved joint efficiency, a high level of penetration is needed.

Abstract: Screening of the toxic active compounds from the ethyl acetate fraction of the sponge Dysidea sp. from Hoga Island, Wakatobi National Park. This study aims to determine the toxic properties of the ethyl acetate fraction of sponge Dysidea sp. Isolation was carried out by extraction method using methanol as solvent, then the extract was partitioned using various solvents, such as N-Hexane, Dichloromethane, Ethyl Acetate and Acetone. The obtained fraction was then tested for toxicity using the Brine Shrimp Lethality Test (BSLT) and phytochemical tests. Identification of compounds from the fraction that have toxic properties were then identified using Liquid Chromatography – High Resolution Mass Spectrometry (LC-HRMS). The ethyl acetate fraction obtained was 1.5 grams in the form of a green solid paste. LC-HRMS analysis showed that the ethyl acetate fraction contained 3 reported compounds and 2 unreported compounds.

Abstract: In this paper, based on the first principles, the exchange correlation functional (GGA) and modified functional (PBE) are used for the calculation of Cu-Cr-Sn high strength and high conductivity copper alloy. The cloud high-throughput cloud computing and screening platform such as Matcloud and cluster expansion method are mainly used. Starting from the most basic components of micro atoms, electrons, ions and energy bands, the high-throughput crystal structure modeling and screening optimization algorithm are adopted, The electronic structure, electromigration and diffusivity of the matrix and the second phase of the material were studied. The theoretical criteria for the collaborative optimization and control of the key performance parameters of the matrix and the characteristic microstructure were established. The characteristic microstructure and material component sequences with excellent mechanical, electrical and thermodynamic properties were predicted and screened.

Abstract: Bacterial cellulose (BC), produced by some bacteria has received attention because its high purity and robust characteristics enable its use in medicine and industry. This study aimed to screen bacteria capable of producing BC from fruits, and to optimize the BC production in both traditional YE yeast fermentation and Schramm and Hestrin (SH) media. The rice washing drainage without any pretreatment as the sole carbon source in the yeast medium was also investigated for BC production in both static and agitated cultures. The bacterial strain Li1 isolated from apple (Malus pumila) was identified as Komagataeibacter (Gluconacetobacter) nataicola based on 16S rDNA sequence analysis. K. nataicola Li1 cultured in a YE medium produced significantly more BC than that in a SH medium in the static culture. Moreover, the weight yields of dry BC films obtained from rice washing drainage and YE media in the static cultures were not significantly different. However, in the agitated culture, the weight yields of dry BC films were more significant in the YE medium than in rice washing drainage medium. In addition, the structure and properties of BC were determined using SEM, FTIR, DSC and XRD. This study shows that rice washing drainage can be used as the carbon source for BC production by K. nataicola Li1.