Optimisation of Negative Fixed Charge Based Edge Termination for Vertical GaN Schottky Devices

This study focuses on the impact of negative fixed charge, achieved through fluorine (F) implantation, on breakdown voltage (BV) enhancement in vertical GaN Schottky diodes. Several device and implant-related parameters are examined using Synopsys Sentaurus TCAD simulations in order to determine the optimum fixed negative charge concentration required to achieve the highest BV. The simulated structure consisted of a Schottky diode with a box consisting of negative fixed charges to achieve the edge termination of the Schottky device. An empirical equation is proposed to determine the optimum fixed charge concentration for the highest BV based on depth. The simulation also considered implantation profiles derived from SIMS data from an actual device implanted with multi-energy and multi-dose F. It is demonstrated that the BV has a similar dependence on the key parameters like in the box profile. In summary, this work provides valuable insights into optimizing edge termination techniques using negative fixed charge for improved BV in vertical GaN power devices

Adaptive Multi-Agent System and Mixed Integer Linear Programming Optimization Comparison for Grid Stability and Commitment Mismatch in Smart Grids

International audienceExisting electrical networks are going through a transition and distributed energy resource, if not managed properly, can hinder this transition. Uncontrolled introduction of photovoltaics and electric vehicles in distribution networks would lead to substantial issues such as commitment mismatches, line congestions, voltage deviations, etc. This paper presents the use of a classical approach, mixed integer linear programming optimization, and a novel approach, adaptive multi-agent system, to solve the highlighted distribution side challenges by utilizing electric vehicles' storage capacity. This comparison serves as a great tool to benchmark the performance of the under-development adaptive multi-agent system methodology

Biomarkers of oxidative stress and protein–protein interaction in chronic obstructive pulmonary disease

<p><b>Content:</b> The increased oxidative stress in chronic obstructive pulmonary disease (COPD) patients is the result of increased inhaled oxidants, generated by various cells of the airways.</p> <p><b>Objective:</b> The investigation included measurements of malondiadehyde (MDA), uric acid, ascorbic acid, and matrix metalloproteinase-12 (MMP-12) in COPD patient. We also performed genetic analysis for protein–protein interaction (PPI) network.</p> <p><b>Materials and methods:</b> The study was conducted on healthy subjects with normal lung function (NS, 14 subjects) and 28 patients (Global Initiative for Chronic Obstructive Lung Disease (Gold) 1 and Gold 2) with COPD.</p> <p><b>Results:</b> There was significant (<i>p</i> < .001) increase in MMP-12, MDA and uric acid levels as compared to healthy controls. A significant (<i>p</i> < .001) decline in ascorbic acid level was observed in COPD patients. The PPI was found to be 0.833 which indicated that proteins present in COPD are linked.</p> <p><b>Discussion and conclusion:</b> This study suggests oxidative stress plays an important role in COPD and the PPI provide indication that proteins present in COPD are linked.</p

Screening of Mungbean [Vigna radiata (L.) Wilczek] Genotypes against Cercospora Leaf Spot Caused by (Cercospora canescens) for Disease Resistance

In India, where vegetarianism is the norm, mungbean [Vigna radiata (L.) Wilczek] is a significant source of proteins, minerals, and vitamins. One of the most significant fungal diseases, Cercospora leaf spot caused by Cercospora canescens, appears every year with varying intensity and significantly reduces yield. The objective of the current studies was to test 100 genotypes for resistance to Cercospora canescens in vivo at the Student's Instructional Farm (S.I.F.) A.N.D.U.A. &amp;T., Kumarganj, Ayodhya. According to the rating system, which is based on the severity of the disease, different genotypes were assigned to different grades. Out of total test entries 13 genotypes LGG 607, PM 14- 3, AKM 12-28, VGG 16- 036, Pusa 171, Pusa 172, RMG 1092, RMG 1097, JLM 302-46, IPM 312-19, IPM 312-20, MGG 387 were found free from infection, 18 genotypes SKNM 1502, COGG 13-39 , PM 1511, Type 44, , DDG3, VGG 05-006, TRAM 1, Asha ,BPMR 145, IPM 02-14, TMB -36, CO -6, BMU, MH 805, MH 2-15, MH 421, MVSKAN, Pusa 0672, were found highly resistant 14 genotypes were noticed susceptible and only 3 genotypes were recorded highly susceptible

Influence of Fluorine implantation on the electrical characteristics of GaN-on-GaN vertical Schottky and P-N diodes

International audienceGaN-based power devices have been gaining popularity in recent years thanks to GaN properties such as wide bandgap, high electron mobility, and high breakdown field strength, allowing low Ron, and high-frequency operation. Lateral GaN devices, which are grown on a foreign substrate like Si and sapphire [1], have already been commercialized and have been able to achieve much better performance compared to their silicon counterparts. However, these devices are unable to achieve sufficiently high breakdown voltage (BV>1kV). One alternative to boost the breakdown voltage and lower Ron is to have vertical devices grown on a native GaN substrate. These devices still suffers from premature breakdown and high reverse leakage due to electric field crowding at the junction edge. This issue can be resolved by creating an effective edge termination either by using Mg implantation [2] to create a p-doped region or by alternate species implantation by Nitrogen [3] or Argon [4] to create a resistive region at the junction edge. However, due to the difficulty in creating p-GaN by ion implantation due to compensation by Hydrogen and large activation energy of ~170 meV, alternate species of implantation is preferred. Fluorine ion implantation [5] is an attractive alternative as it can form a negative fixed charge owning to its highest electronegativity thus spread the electric field away from the contact and can also modulate the free charge carrier in GaN.In this study, P-N and Schottky structures are fabricated using multi energy Fluorine implantation as an edge termination. The influence of the implant on the electrical characteristics is studied by varying the implant overlap beneath the contact. µ-Raman scanning of the device suggests a reduction in free charge concentration in the implanted region, and an increase in the built-in potential obtained through C-V measurements compared to the device with no implantation. The influence of implantation on the electrical characteristics (B-V, I-V, and C-V) is analyzed and TCAD simulations using Synopsys® SentaurusTM are performed to help interpret the results

Influence of Fluorine implantation on the electrical characteristics of GaN-on-GaN vertical Schottky and P-N diodes

International audienceGaN-based power devices have been gaining popularity in recent years thanks to GaN properties such as wide bandgap, high electron mobility, and high breakdown field strength, allowing low Ron, and high-frequency operation. Lateral GaN devices, which are grown on a foreign substrate like Si and sapphire [1], have already been commercialized and have been able to achieve much better performance compared to their silicon counterparts. However, these devices are unable to achieve sufficiently high breakdown voltage (BV>1kV). One alternative to boost the breakdown voltage and lower Ron is to have vertical devices grown on a native GaN substrate. These devices still suffers from premature breakdown and high reverse leakage due to electric field crowding at the junction edge. This issue can be resolved by creating an effective edge termination either by using Mg implantation [2] to create a p-doped region or by alternate species implantation by Nitrogen [3] or Argon [4] to create a resistive region at the junction edge. However, due to the difficulty in creating p-GaN by ion implantation due to compensation by Hydrogen and large activation energy of ~170 meV, alternate species of implantation is preferred. Fluorine ion implantation [5] is an attractive alternative as it can form a negative fixed charge owning to its highest electronegativity thus spread the electric field away from the contact and can also modulate the free charge carrier in GaN.In this study, P-N and Schottky structures are fabricated using multi energy Fluorine implantation as an edge termination. The influence of the implant on the electrical characteristics is studied by varying the implant overlap beneath the contact. µ-Raman scanning of the device suggests a reduction in free charge concentration in the implanted region, and an increase in the built-in potential obtained through C-V measurements compared to the device with no implantation. The influence of implantation on the electrical characteristics (B-V, I-V, and C-V) is analyzed and TCAD simulations using Synopsys® SentaurusTM are performed to help interpret the results

Electrical Transport Characteristics of Vertical GaN Schottky-Barrier Diode in Reverse Bias and Its Numerical Simulation

We investigated the temperature-dependent reverse characteristics (JR-VR-T) of vertical GaN Schottky-barrier diodes with and without a fluorine-implanted edge termination (ET). To understand the device leakage mechanism, temperature-dependent characterizations were performed, and the observed reverse current was modeled through technology computer-aided design. Different levels of current were observed in both forward and reverse biases for the ET and non-ET devices, which suggested a change in the conduction mechanism for the observed leakages. The measured JR-VR-T characteristics of the non-edge-terminated device were successfully fitted in the entire temperature range with the phonon-assisted tunneling model, whereas for the edge-terminated device, the reverse characteristics were modeled by taking into account the emission of trapped electrons at a high temperature and field caused by Poole–Frenkel emission

Influence of fluorine implantation on the physical and electrical characteristics of GaN-on-GaN vertical Schottky diode

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Mobility Extraction Using Improved Resistance Partitioning Methodology for Normally-OFF Fully Vertical GaN Trench MOSFETs

International audienceIn this work, fully vertical GaN trench MOSFETs were fabricated and characterized to evaluate their electrical performances. Transistors show a normally-OFF behavior with a high ION/IOFF (~109) ratio and a significantly small gate leakage current (10−11 A/mm). Thanks to an improved resistance partitioning method, the resistances of the trench bottom and trench channel were extracted accurately by taking into account different charging conditions. This methodology enabled an estimation of the effective channel and bottom mobility of 11.1 cm2/V·s and 15.1 cm2/V·s, respectively