Effects of Proton Irradiation on the Current Characteristics of SiN-Passivated AlGaN/GaN MIS-HEMTs Using a TMAH-Based Surface Pre-Treatment

This study investigated the combined effects of proton irradiation and surface pre-treatment on the current characteristics of Gallium Nitride (GaN)-based metal-insulator-semiconductor high-electron-mobility-transistors (MIS-HEMTs) to evaluate the radiation hardness involved with the Silicon Nitride (SiN) passivation/GaN cap interface. The impact of proton irradiation on the static and dynamic current characteristics of devices with and without pre-treatment were analyzed with 5 MeV proton irradiation. In terms of transfer characteristics before and after the proton irradiation, the drain current of the devices without and with pre-treatment were reduced by an increase in sheet and contact resistances after the proton irradiation. In contrast with the static current characteristics, the gate-lag characteristics of the device with pre-treatment were significantly degenerated. In the device with pre-treatment, the hydrogen passivation for surface states of the GaN cap was formed by the pre-treatment and SiN deposition processes. Since the hydrogen passivation was removed by the proton irradiation, the newly created vacancies resulted in the degeneration of gate-lag characteristics. After nine months in an ambient atmosphere, the gate-lag characteristics of the device with pre-treatment were recovered because of the hydrogen recombination. These results demonstrated that the radiation hardness of MIS-HEMTs was affected by the SiN/GaN interface quality.

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Effect of lateral Gate Design on the Performance of Junctionless Lateral Gate Transistors

Electronics ◽

10.3390/electronics8050538 ◽

2019 ◽

Vol 8 (5) ◽

pp. 538

Author(s):

Farhad Larki ◽

Md Shabiul Islam ◽

Arash Dehzangi ◽

Mohammad Tariqul Islam ◽

Hin Yong Wong

Keyword(s):

Computer Aided Design ◽

Three Dimensional ◽

Drain Current ◽

Channel Length ◽

Influential Factors ◽

Gate Length ◽

Current Characteristics ◽

Lateral Gate ◽

The Impact ◽

Gate Design

In this paper, we investigate the effect of lateral gate design on performance of a p-type double lateral gate junctionless transistors (DGJLTs) with an air gate gap. The impact of lateral gate length, which modifies the real channel length of the device and gate gap variation down to 50 nm which have been found to be the most influential factors in the performance of the device have been comprehensively investigated. The characteristics are demonstrated and compared with a nominal DGJLTs through three-dimensional technology computer-aided design (TCAD) simulation. At constant channel geometry (thickness and width), when the lateral gate length decreases, the results show constant flatband drain current characteristics while the OFF state current (IOFF) increases significantly. On the other hand, by decreasing the air gap the subthreshold current considerably decreases while the flatband current is constant. Moreover, at a certain gate gap, the gates lose control over the channel and the device simply works as a resistor. Electric field component, carriers’ density, band edge energies, and recombination rate of the carriers inside the channel in depletion and accumulation regimes are analysed to interpret the variation of output characteristics.

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Characteristics of Two-Stage Γ-Gate on AlGaAs/InGaAs/AlGaAs DH-HEMTs by Using AlGaAs/InGaP Etching-Stop Layers

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.415-417.1327 ◽

2011 ◽

Vol 415-417 ◽

pp. 1327-1332

Author(s):

Jia Chuan Lin ◽

Fu Xiang Zeng ◽

Jia Na Wei ◽

Chi Ting Liu ◽

Meng Kai Hsu ◽

...

Keyword(s):

Electric Field ◽

Drain Current ◽

High Electron Mobility Transistors ◽

Structure Design ◽

Common Source ◽

High Electron ◽

Two Stage ◽

Electron Mobility Transistors ◽

Field Peak ◽

Current Characteristics

Al0.22Ga0.78As/In0.18Ga0.82As/Al0.22Ga0.78As double heterojunction high electron mobility transistors (DH-HEMTs) with gate structures of traditional planar gate (PG), one-stage gamma-gate (1SΓG) and two-stage gamma-gate (2SΓG) formed by using the Al0.22Ga0.78As/In0.49Ga0.51P etch-stop layers (ESL) are simulated and presented in this work. Based on this proposed ESL structure design, the fabrication and implementation of studied DH-HEMT device with 1SΓG and 2SΓG could be expected. Both ΓG-structure devices show the better electric field property compared to PG-device. Simulated results reveal that there are no significant differences in common-source voltage-current characteristics among all studied devices. The obtained drain current density and transconductance of all studied devices are about 220 mAmm-1and 265 mSmm-1. However, the current stability of ΓG-devices with larger bias operation would be improved due to its edge-effect of ΓG extended-region. In addition, the electric field intensity under the gate-footprint is effectively reduced by both studied ΓG structures. The electric field peak value of PG-device is 498 kV cm-1, and it would be reduced down to about 210 kVcm-1and 178 kVcm-1for 1SΓG- and 2SΓG-device, respectively. On the other hand, some frequency property dropping is observed from studied device with 1SΓG or 2SΓG due to the side-edge extension of ΓG-device would create the additional parasitic capacitance. The obtained cut-off frequencies are 15 GHz, 10.5 GHz and 10 GHz for PG-, 1SΓG- and 2SΓG-device (at VGS=+5 V and VGS=-0.75 V), respectively.

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Simulation Study of the Impact of Traps in GaN Substrates on the Electrical Characteristics of AlGaN/GaN HEMTs with Thin Channel Layers

10.21203/rs.3.rs-363450/v1 ◽

2021 ◽

Author(s):

Toshiyuki Oishi ◽

Kaito Ito

Keyword(s):

Leakage Current ◽

Drain Current ◽

High Electron ◽

Transient Responses ◽

Trade Off ◽

Trap Concentration ◽

Al Content ◽

Thin Channel ◽

Gan Hemts ◽

The Impact

Abstract GaN substrates are promising candidates for GaN high electron mobility transistors (HEMTs) due to their epitaxial layer growth with a low defect density. In this study, technology computer-aided design simulations were executed to design the GaN HEMTs on semi-insulating GaN substrates with thin channel layers. Traps in the GaN substrates played a role in suppressing drain-leakage currents, although degrading transient responses changed the bias from off to on-state for the 0.02-μm thin channel layer. A trade-off relationship between the drain-leakage current and transient response is occurred by changing the trap concentration in the GaN substrates. The AlGaN back-barrier structure has been found to be highly effective in suppressing the drain-leakage current in low-trap-concentration GaN substrates. The trade-off relationship improved by adopting the back-barrier layers, and the maximum drain current decreased. The drain-current reduction compensated by increasing the Al content in the barriers without degrading the trade-off relationship. Therefore, for GaN HEMTs that have low-trap-concentration GaN substrates combined with the back-barrier layer, a high-Al-content barrier have characteristics that are favorable for the trade-off relationship in the case of thin channel layers. Moreover, the traps in GaN substrates were found to affect low-frequency S 21 , which is important for linearity of the power amplifier, as critically as the transient responses.

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Design and Parametric Analysis of GaN on Silicon High Electron Mobility Transistor for RF Performance Enhancement

10.21203/rs.3.rs-865726/v1 ◽

2021 ◽

Author(s):

Jeetendra Singh ◽

Archana Verma ◽

Vijay Kumar Tewari ◽

Shailendra Singh

Keyword(s):

Electron Mobility ◽

High Performance ◽

Performance Enhancement ◽

Drain Current ◽

High Electron Mobility Transistor ◽

Channel Length ◽

High Electron ◽

High Electron Mobility ◽

Rf Performance ◽

The Impact

Abstract The need of performance enhancement at the RF and millimeter wave is highly desirable to eliminate the heating effects and power dissipation. Silicon substarte found to be a suitable candidate which reduces about 70% channel temperature than sapphire. To achieve high performance, a GaN on the Silicon substrate high electron mobility transistor is designed and its various performance paramters are analyzed by varying the design specifications. Moreover, the problem of blocking voltage improvement is resolved by epitaxial design approach. Since, threshold voltage, doping-level, work-function of gate material and channel length are considered as some of the important parameters while device modeling. Therefore, the impact of these parameters is examined and analyzed to enehace the performance and reliability of the device for RF applications. The performance parameters like trans-conductance, drain current curves are plotted at different state of device physical and electrical parameters. Results exhibits maximum value of transconductance gm=13 milli-mho, minimum gate capacitance Cg=0.5pf, wheras Vth is varied between − 0.25 volts to 0.25 volts.

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Pre-treatment clinical and gene expression patterns predict developmental change in early intervention in autism

Molecular Psychiatry ◽

10.1038/s41380-021-01239-2 ◽

2021 ◽

Author(s):

Michael V. Lombardo ◽

Elena Maria Busuoli ◽

Laura Schreibman ◽

Aubyn C. Stahmer ◽

Tiziano Pramparo ◽

...

Keyword(s):

Gene Expression ◽

Treatment Outcome ◽

Early Intervention ◽

Developmental Change ◽

Expression Patterns ◽

Gene Expression Patterns ◽

Time In Treatment ◽

Pre Treatment ◽

Blood Leukocyte ◽

The Impact

AbstractEarly detection and intervention are believed to be key to facilitating better outcomes in children with autism, yet the impact of age at treatment start on the outcome is poorly understood. While clinical traits such as language ability have been shown to predict treatment outcome, whether or not and how information at the genomic level can predict treatment outcome is unknown. Leveraging a cohort of toddlers with autism who all received the same standardized intervention at a very young age and provided a blood sample, here we find that very early treatment engagement (i.e., <24 months) leads to greater gains while controlling for time in treatment. Pre-treatment clinical behavioral measures predict 21% of the variance in the rate of skill growth during early intervention. Pre-treatment blood leukocyte gene expression patterns also predict the rate of skill growth, accounting for 13% of the variance in treatment slopes. Results indicated that 295 genes can be prioritized as driving this effect. These treatment-relevant genes highly interact at the protein level, are enriched for differentially histone acetylated genes in autism postmortem cortical tissue, and are normatively highly expressed in a variety of subcortical and cortical areas important for social communication and language development. This work suggests that pre-treatment biological and clinical behavioral characteristics are important for predicting developmental change in the context of early intervention and that individualized pre-treatment biology related to histone acetylation may be key.

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Time-to-Treatment in Oral Cancer: Causes and Implications for Survival

Cancers ◽

10.3390/cancers13061321 ◽

2021 ◽

Vol 13 (6) ◽

pp. 1321

Author(s):

Constanza Saka-Herrán ◽

Enric Jané-Salas ◽

Antoni Mari-Roig ◽

Albert Estrugo-Devesa ◽

José López-López

Keyword(s):

Oral Cancer ◽

Previous Treatment ◽

Diagnostic Procedures ◽

Original Data ◽

Primary Treatment ◽

Medical Attention ◽

Time Interval ◽

Pre Treatment ◽

The Impact ◽

Lack Of Knowledge

The purpose of this review was to identify and describe the causes that influence the time-intervals in the pathway of diagnosis and treatment of oral cancer and to assess its impact on prognosis and survival. The review was structured according to the recommendations of the Aarhus statement, considering original data from individual studies and systematic reviews that reported outcomes related to the patient, diagnostic and pre-treatment intervals. The patient interval is the major contributor to the total time-interval. Unawareness of signs and/or symptoms, denial and lack of knowledge about oral cancer are the major contributors to the process of seeking medical attention. The diagnostic interval is influenced by tumor factors, delays in referral due to higher number of consultations and previous treatment with different medicines or dental procedures and by professional factors such as experience and lack of knowledge related to the disease and diagnostic procedures. Patients with advanced stage disease, primary treatment with radiotherapy, treatment at an academic facility and transitions in care are associated with prolonged pre-treatment intervals. An emerging body of evidence supports the impact of prolonged pre-treatment and treatment intervals with poorer survival from oral cancer.

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Comparison of Selected Immune and Hematological Parameters and Their Impact on Survival in Patients with HPV-Related and HPV-Unrelated Oropharyngeal Cancer

Cancers ◽

10.3390/cancers13133256 ◽

2021 ◽

Vol 13 (13) ◽

pp. 3256

Author(s):

Adam Brewczyński ◽

Beata Jabłońska ◽

Agnieszka Maria Mazurek ◽

Jolanta Mrochem-Kwarciak ◽

Sławomir Mrowiec ◽

...

Keyword(s):

Prognostic Factors ◽

Oropharyngeal Cancer ◽

Hematological Parameters ◽

White Blood Cells ◽

Post Treatment ◽

Neutrophil Lymphocyte Ratio ◽

Lymphocyte Ratio ◽

Hpv Status ◽

Pre Treatment ◽

The Impact

Several immune and hematological parameters are associated with survival in patients with oropharyngeal cancer (OPC). The aim of the study was to analyze selected immune and hematological parameters of patients with HPV-related (HPV+) and HPV-unrelated (HPV-) OPC, before and after radiotherapy/chemoradiotherapy (RT/CRT) and to assess the impact of these parameters on survival. One hundred twenty seven patients with HPV+ and HPV− OPC, treated with RT alone or concurrent chemoradiotherapy (CRT), were included. Patients were divided according to HPV status. Confirmation of HPV etiology was obtained from FFPE (Formalin-Fixed, Paraffin-Embedded) tissue samples and/or extracellular circulating HPV DNA was determined. The pre-treatment and post-treatment laboratory blood parameters were compared in both groups. The neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), monocyte/lymphocyte ratio (MLR), and systemic immune inflammation (SII) index were calculated. The impact of these parameters on overall (OS) and disease-free (DFS) survival was analyzed. In HPV+ patients, a high pre-treatment white blood cells (WBC) count (>8.33 /mm3), NLR (>2.13), SII (>448.60) significantly correlated with reduced OS, whereas high NLR (>2.29), SII (>462.58) significantly correlated with reduced DFS. A higher pre-treatment NLR and SII were significant poor prognostic factors for both OS and DFS in the HPV+ group. These associations were not apparent in HPV− patients. There are different pre-treatment and post-treatment immune and hematological prognostic factors for OS and DFS in HPV+ and HPV− patients. The immune ratios could be considered valuable biomarkers for risk stratification and differentiation for HPV− and HPV+ OPC patients.

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Porphyromonas Gingivalis Infection Induces Synaptic Failure via Increased IL-1β Production in Leptomeningeal Cells

Journal of Alzheimer s Disease ◽

10.3233/jad-210031 ◽

2021 ◽

pp. 1-17

Author(s):

Wanyi Huang ◽

Fan Zeng ◽

Yebo Gu ◽

Muzhou Jiang ◽

Xinwen Zhang ◽

...

Keyword(s):

Porphyromonas Gingivalis ◽

Nlrp3 Inflammasome ◽

Cortical Neurons ◽

Inflammasome Activation ◽

Memory Decline ◽

Periodontal Bacteria ◽

Nlrp3 Inflammasome Activation ◽

Synaptic Failure ◽

Pre Treatment ◽

The Impact

Background: Studies have reported that synaptic failure occurs before the Alzheimer’s disease (AD) onset. The systemic Porphyromonas gingivalis (P. gingivalis) infection is involved in memory decline. We previously showed that leptomeningeal cells, covering the brain, activate glial cells by releasing IL-1β in response to systemic inflammation. Objective: In the present study, we focused on the impact of leptomeningeal cells on neurons during systemic P. gingivalis infection. Methods: The responses of leptomeningeal cells and cortical neurons to systemic P. gingivalis infection were examined in 15-month-old mice. The mechanism of IL-1β production by P. gingivalis infected leptomeningeal cells was examined, and primary cortical neurons were treated with P. gingivalis infected leptomeningeal cells condition medium (Pg LCM). Results: Systemic P. gingivalis infection increased the expression of IL-1β in leptomeninges and reduced the synaptophysin (SYP) expression in leptomeninges proximity cortex in mice. Leptomeningeal cells phagocytosed P. gingivalis resulting in lysosomal rupture and Cathepsin B (CatB) leakage. Leaked CatB mediated NLRP3 inflammasome activation inducing IL-1β secretion in leptomeningeal cells. Pg LCM decreased the expression of synaptic molecules, including SYP, which was inhibited by an IL-1 receptor antagonist pre-treatment. Conclusion: These observations demonstrate that P. gingivalis infection is involved in synaptic failure by inducing CatB/NLRP3 inflammasome-mediated IL-1β production in leptomeningeal cells. The periodontal bacteria-induced synaptic damage may accelerate the onset and cognitive decline of AD.

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Many-impurity scattering on the surface of a topological insulator

Scientific Reports ◽

10.1038/s41598-021-84801-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

José Luis Hernando ◽

Yuriko Baba ◽

Elena Díaz ◽

Francisco Domínguez-Adame

Keyword(s):

Green’S Function ◽

Green's Function ◽

Topological Insulator ◽

Disordered Systems ◽

Spectral Properties ◽

Random Distribution ◽

Surface States ◽

Impurity Scattering ◽

Self Consistent ◽

The Impact

AbstractWe theoretically address the impact of a random distribution of non-magnetic impurities on the electron states formed at the surface of a topological insulator. The interaction of electrons with the impurities is accounted for by a separable pseudo-potential method that allows us to obtain closed expressions for the density of states. Spectral properties of surface states are assessed by means of the Green’s function averaged over disorder realisations. For comparison purposes, the configurationally averaged Green’s function is calculated by means of two different self-consistent methods, namely the self-consistent Born approximation (SCBA) and the coherent potential approximation (CPA). The latter is often regarded as the best single-site theory for the study of the spectral properties of disordered systems. However, although a large number of works employ the SCBA for the analysis of many-impurity scattering on the surface of a topological insulator, CPA studies of the same problem are scarce in the literature. In this work, we find that the SCBA overestimates the impact of the random distribution of impurities on the spectral properties of surface states compared to the CPA predictions. The difference is more pronounced when increasing the magnitude of the disorder.

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Mechanical, Thermal and Rheological Properties of Polyethylene-Based Composites Filled with Micrometric Aluminum Powder

Materials ◽

10.3390/ma13051242 ◽

2020 ◽

Vol 13 (5) ◽

pp. 1242

Author(s):

Olga Mysiukiewicz ◽

Paulina Kosmela ◽

Mateusz Barczewski ◽

Aleksander Hejna

Keyword(s):

Mechanical Properties ◽

Melt Flow Index ◽

Tensile Tests ◽

Mechanical Analysis ◽

Flow Index ◽

Scanning Calorimetry ◽

Metal Composites ◽

Pre Treatment ◽

The Impact ◽

Properties Of Composites

Investigations related to polymer/metal composites are often limited to the analysis of the electrical and thermal conductivity of the materials. The presented study aims to analyze the impact of aluminum (Al) filler content (from 1 to 20 wt%) on the rarely investigated properties of composites based on the high-density polyethylene (HDPE) matrix. The crystalline structure, rheological (melt flow index and oscillatory rheometry), thermal (differential scanning calorimetry), as well as static (tensile tests, hardness, rebound resilience) and dynamic (dynamical mechanical analysis) mechanical properties of composites were investigated. The incorporation of 1 and 2 wt% of aluminum filler resulted in small enhancements of mechanical properties, while loadings of 5 and 10 wt% provided materials with a similar performance to neat HDPE. Such results were supported by the lack of disturbances in the rheological behavior of composites. The presented results indicate that a significant content of aluminum filler may be introduced into the HDPE matrix without additional pre-treatment and does not cause the deterioration of composites’ performance, which should be considered beneficial when engineering PE/metal composites.

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