Defect and Diffusion Forum Vol. 425

Abstract: Buffer layer optimization is a critical technique to mitigate defect propagation from substrate to epilayer, reduce stress, and prevent generation of ingrown defects. In the present study, the impact of dopant transition from substrate to the buffer layer on various epilayer defects was investigated. It was found that a ramped transition of the dopant concentration from substrate to buffer layer is beneficial for reduction of basal plane dislocations in the epilayer compared to an abrupt doping transition. This reduction of defects can be attributed to reduced stress at the substrate-to-buffer layer transition. Tests on buffer layer growth rates also revealed that higher growth rates reduce BPDs (basal plane dislocations) in the epilayers. We believe that BPD conversion in epilayers grown at higher growth rates is energetically more favorable than the conversion at slower growth rates resulting in the observed reduced BPDs at higher growth rates.

Abstract: In the previous report [1], we proposed the S-EVC (Selective Expansion-Visualization-Contraction) method (Fig. 1) that effectively screens for malignant BPDs (basal plane dislocations) in the drift and buffer layers, which expand to SSFs (Shockley-type stacking faults), leading to forward voltage degradation. The method intentionally utilizes the REDG (recombination enhanced dislocation glide) mechanism by UV (ultraviolet) irradiation in wafer sorting to replace the so-called burn-in (accelerated current stress) process, which is time-consuming during mass production. In the report, triangular SSFs were examined to verify the effectiveness of the method, but they only occupy a much smaller area of the active region on the chip than bar shaped SSFs. In this study, to improve the S-EVC method to be more practical, we focused on the more serious bar shaped SSFs which have a non-negligible impact on electrical characteristics. The bar shaped SSFs are mostly expanded from TED (threading edge dislocation)-converted BPD at or below the substrate epitaxial layer interface. In PL (photoluminescence) observation by a 710 nm LPF (long-pass filter), the TED-converted BPD and the complete TED extended from the bottom of the substrate are observed as the same dark spot, but it was confirmed that both can be distinguished by the presence or absence of their SSF expansion by UV irradiation. In addition, in order to confirm the validity of the S-EVC method even on the virgin epi wafer, UV irradiation was performed on both the aluminum doped PN structured wafer and the virgin epi wafer, and the similar SSF expansion was observed. Meanwhile, the correlation between UV irradiation and forward voltage degradation was quantified using PiN diodes by comparing the glide velocity of 30°Si (g) core partials for bar shaped SSFs by UV irradiation stress with that by current stress.

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: Abstract. in this Study, Activated Carbon was Created by Physically Activating Potato Peel Waste (PPW) with Carbon Dioxide. the Potential of this Approach, which Uses Carbon Dioxide to Produce Actuation Carbon (AC) from Precursor Potato Peel Waste, has been Investigated. Utilizing x-Ray Diffraction Analysis, Scanning Electron Microscopy, and Atomic Force Microscopy, the Microstructure of the Activated Carbon was Examined. the Average Crystallite Size was Affected by Employing Varied Periods for the Activation Process, as Seen by the Crystallite Size of the High-Intensity Peaks of the Precursor Potato Peel Waste at Various Drying Times and the Activated Products. after 60 Minutes of Drying, the Activation Stage was under Ideal Conditions, and in Comparison to the other Times, a Size of 325 Nm was Also Attained with the Rest of the Periods, as well as a High Adhesion Elevation Surface Region for the Carbon. the Activated Carbon Produced Using Physical Activation Showed a Surface Area as High as 1733 m²/g with a Pore Volume of 0.45 cm³/g, whereas the Precursor Showed a Surface Area of < 4 m²/g. this Investigation Aims to Modify the Surface of Activated Carbon without Significantly Altering its Structural Parameters for Use in Future Renewable Energy Sources and to Make the Synthesis of such Materials more Potent, more Eco-Friendly, and Less Expensive.

Abstract: The preparation of apolymeric membrane by a chemical method was introduced for a Polymer Electrolyte Membrane (PEM) fuel cell. Cobalt oxide (Co₃O₅) was used in the coexistent of two polymers to speed up the reaction process and to obtain the best results. Different tests were implemented along the research to evaluate the new membrane such as X-ray, Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FTIR). The new membrane shown an increment both in the current (I) and the volume of Hydrogen (H₂) at a constant voltage (V).

Abstract: Microbial fuel cells (MFCs) are considered as an economical and sustainable technology for various applications. This study has designed four single-chamber SCMFCs that composed of graphite plates as electrodes and used wastewater as a substrate for microorganisms. In order to evaluate the performance of SCMFC, the experiments were executed in a batch mode over 18 days at various types of salt bridge. Four salt bridges are used namely (KCl, NaCl, KNO₃, and Cotton Rope). It was found that KCl generated a maximum voltage of 989 mv. The following results were obtained for wastewater investigated parameters: COD = 94%, PO₄ = 88.4%, NO₃ = 88%, TSS = 80%, and Fe = 76%, respectively at 1 M KCl. The experiment was then carried out using different values of KCl (1, 1.5, 2, 3 M). It was found that at a molar concentration of 1.5, 1422 mv of maximum voltage has been generated. Results for wastewater treatment demonstrated that COD of 81%, PO4 of 78.2%, NO3 of 79%, TSS of 80%, and Fe of 84%.

Abstract: Using Municipal solid waste as a fuel for electric power generation is considered of an important matter for the engineers and scientists now a day. The municipal solid waste (MSW) that is collected in Baghdad city the capital of Iraq is estimated to be 14,368 ton /day for year 2029 with population of 10,769,040. In this paper an MSW - based power generation plant is suggested to be constructed in Baghdad as there are three final disposals of MSW one of them is Nabaai disposal facility which is considered the main final disposal of MSW in Baghdad as 85% of the MSW is deposited in it. The calculation of the power produced by MSW-based power plant for Baghdad is 299 MW which is greatly assists in relieving the power generation crisis in Iraq.