Impact of Gate Offset in Gate Recess on DC and RF Performance of InAlAs/InGaAs InP-based HEMTs

2021 ◽  
Author(s):  
Shu-rui Cao ◽  
Rui-ze Feng ◽  
Bo Wang ◽  
Tong Liu ◽  
Peng Ding ◽  
...  
Keyword(s):  
Drain Current ◽  
Rf Measurement ◽  
Novel Technology ◽  
Drain Side ◽  
Source Resistance ◽  
Selection For ◽  
Definition Of ◽  
Rf Performance ◽  
Gate Recess ◽  
Output Conductance

Abstract In this work, a set of 100-nm gate-length InP-based HEMTs were designed and fabricated with different gate offsets in gate recess. A novel technology was proposed for independent definition of gate recess and T-shaped gate by electron beam lithography. DC and RF measurement was conducted. With the gate offset varying from drain side to source side, the maximum drain current (Ids,max) and transconductance (gm,max) increased. In the meantime, f T decreased while f max increased, and the highest f max of 1096 GHz was obtained. It can be explained by the increase of gate-source capacitance and the decrease of gate-drain capacitance and source resistance. Output conductance was also suppressed by gate offset toward source side. This provides simple and flexible device parameter selection for HEMTs of different usage.

MESFETs on H-terminated Single Crystal Diamond

2009 ◽  
Vol 1203 ◽  
Author(s):  
Paolo Calvani ◽  
Maria Cristina Rossi ◽  
Gennaro Conte ◽  
Stefano Carta ◽  
Ennio Giovine ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Single Crystal ◽  
Oscillation Frequency ◽  
Diamond Films ◽  
Drain Current ◽  
Gate Length ◽  
Maximum Oscillation Frequency ◽  
Single Crystal Diamond ◽  
Device Geometry ◽  
Rf Performance

AbstractEpitaxial diamond films were deposited on polished single crystal Ib type HPHT diamond plates of (100) orientation by microwave CVD. The epilayers were used for the fabrication of surface channel MESFET structures having sub-micrometer gate length in the range 200-800 nm. Realized devices show maximum drain current and trasconductance values of about 190 mA/mm and 80 mS/mm, respectively, for MESFETs having 200 nm gate length. RF performance evaluation gave cut off frequency of about 14 GHz and maximum oscillation frequency of more than 26 GHz for the same device geometry.

PATIENT CARE AND STUDENT LEARNING IN A PEDIATRIC CLINIC

PEDIATRICS ◽  
1972 ◽  
Vol 50 (6) ◽  
pp. 847-848
Author(s):  
Robert J. Haggerty
Keyword(s):  
Patient Care ◽  
Student Teaching ◽  
Effective Management ◽  
Patient Dissatisfaction ◽  
Complex Problems ◽  
Teaching Objectives ◽  
Recruitment Procedure ◽  
Outpatient Departments ◽  
Selection For ◽  
Definition Of

Every pediatrician who has taught or worked in university pediatric outpatient departments recognizes the syndrome presented by Duff et al. in this issue of Pediatrics. The diagnosis is clear: effective student teaching is not occurring. The etiology of this problem is complex and not so clear. Some of the causes are inappropriate patient selection for beginning students, lack of effective administrative organization to achieve even limited teaching objectives, and lack of appropriate techniques to diagnose and manage the complex sociomedical problems presented. As a result, student, faculty, and patient dissatisfaction is very high. Effective management of the syndrome is even less clear. As with most complex problems, a clearer definition of the goals is the first step to a solution. What do we want the student to learn? How to gather information from families with such complex social and medical difficulties? Skills in diagnosis and management of common or rare health problems? Change of attitudes? Until each ambulatory program defines its teaching objectives more clearly in behaviorally measurable terms, effective management of the disease "poor patient care and teaching" will continue to elude us. I would, however, suggest the following considerations: 1. The first direct patient experiences which students have in ambulatory settings should be with patients who present considerably less complex problems than those available in most of our outpatient departments, and there should be a wider social class selection for the student's initial experience. To achieve this will require either a different patient recruitment procedure or the use of different settings for such education.

scholarly journals Simulation Study of the Use of AlGaN/GaN Ultra-Thin-Barrier HEMTs with Hybrid Gates for Achieving a Wide Threshold Voltage Modulation Range

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 654
Author(s):  
Shouyi Wang ◽  
Qi Zhou ◽  
Kuangli Chen ◽  
Pengxiang Bai ◽  
Jinghai Wang ◽  
...  
Keyword(s):  
Hole Concentration ◽  
Drain Current ◽  
Device Performance ◽  
Depletion Effect ◽  
Threshold Voltages ◽  
Gate Structure ◽  
Drain Side ◽  
Effective Reduction ◽  
Field Peak ◽  
Thin Barrier

In this work, novel hybrid gate Ultra-Thin-Barrier HEMTs (HG-UTB HEMTs) featuring a wide modulation range of threshold voltages (VTH) are proposed. The hybrid gate structure consists of a p-GaN gate part and a MIS-gate part. Due to the depletion effect assisted by the p-GaN gate part, the VTH of HG-UTB HEMTs can be significantly increased. By tailoring the hole concentration of the p-GaN gate, the VTH can be flexibly modulated from 1.63 V to 3.84 V. Moreover, the MIS-gate part enables the effective reduction in the electric field (E-field) peak at the drain-side edge of the p-GaN gate, which reduces the potential gate degradation originating from the high E-field in the p-GaN gate. Meanwhile, the HG-UTB HEMTs exhibit a maximum drain current as high as 701 mA/mm and correspond to an on-resistance of 10.1 Ω mm and a breakdown voltage of 610 V. The proposed HG-UTB HEMTs are a potential means to achieve normally off GaN HEMTs with a promising device performance and featuring a flexible VTH modulation range, which is of great interest for versatile power applications.

scholarly journals Channel temperature analysis of AlGaN/GaN HEMTs in quasi-static and pulse operation mode

2018 ◽  
Vol 69 (5) ◽  
pp. 390-394
Author(s):  
Martin Florovič ◽  
Róbert Szobolovszký ◽  
Jaroslav Kováč ◽  
Jaroslav Kováč ◽  
Aleš Chvála ◽  
...  
Keyword(s):  
Operation Mode ◽  
Drain Current ◽  
Temperature Dependent ◽  
Saturation Velocity ◽  
Channel Temperature ◽  
Device Reliability ◽  
Source Resistance ◽  
Current Change ◽  
Voltage Saturation

Abstract GaN-based HEMTs’ high potential is deteriorated by self-heating during the operation, this has influence on the electrical properties as well as device reliability. This work is focused on an average channel temperature determination of power AlGaN/GaN HEMT prepared on SiC substrate using quasi-static and pulsed I-V characterization. There was analyzed the drain current change relation to temperature dependent electrical HEMT parameters such as source resistance, threshold voltage, saturation velocity, resp. leakage current which allows to calculate an average channel temperature versus dissipated power for various ambient temperature. Differential temperature of investigated device with and without heatsink was determined. Obtained results were discussed using simulated spatial temperature distribution.

Approach on Component Selection for Ageing-Trend Analysis Within PSA Models

2009 ◽  
Author(s):  
Shahen Poghosyan ◽  
Armen Amirjanyan ◽  
Albert Malkhasyan
Keyword(s):  
Trend Analysis ◽  
Significant Contribution ◽  
Reactor Core ◽  
Component Selection ◽  
Core Damage ◽  
Ageing Effects ◽  
Level 1 ◽  
Selection For ◽  
Definition Of ◽  
Actual Configuration

The major advantage of PSA is the possibility of in-depth qualitative and quantitative analysis of NPP actual configuration with definition of factors introducing a significant contribution to the general risk of reactor core damage. However main lack of the PSA current models is neglect of equipment ageing effects. Neglecting of ageing effects in PSA could lead to incorrectness of risk profile and influent on risk-informed decision making process. To solve this issue incorporation of ageing aspects into PSA models for Armenian NPP Unit 2 was initiated. Implementation of ageing trend analysis for all PSA components is insuperable effort, so the first step of the analysis is component selection activity. This paper is addressing the approach on component selection for ageing-trend analysis within PSA models. Presented approach is based on ageing effect and risk importance data. The procedure was developed and implemented in the framework of ageing aspects incorporation into PSA level 1 model for Armenian NPP Unit 2.

Description of LV pressure-volume relations by time-varying elastance and source resistance

1987 ◽  
Vol 253 (1) ◽  
pp. H83-H90 ◽  
Author(s):  
W. C. Little ◽  
G. L. Freeman
Keyword(s):  
Left Ventricle ◽  
Balloon Occlusion ◽  
Ascending Aorta ◽  
Aortic Flow ◽  
Three Dimensions ◽  
Time Varying ◽  
Source Resistance ◽  
Lv Volume ◽  
Definition Of ◽  
Inotropic Stimulation

If the left ventricle (LV) behaves as a time-varying elastance [E(t)] that is independent of load, then definition of E(t) during normal ejecting beats should permit accurate prediction of LV pressure (LVP) during a maximally afterloaded (isovolumic) beat. We tested this hypothesis in six dogs preinstrumented to measure LVP and aortic flow (Q) and to determine LV volume (V) from three dimensions. LVP and V were varied by caval occlusions. These data were used to determine E(t) and minimal volume required to generate pressure (Vo) at 10-ms intervals during systole using a simple E(t) model, P(t) = E(t) [V(t)-Vo], where P(t) is LVP at any time after the onset of contraction, and V(t) is the LV volume at t. LVP was measured during isovolumic beats generated by sudden balloon occlusion of the ascending aorta. The simple E(t) model accurately predicted isovolumic LVP during the first 70 ms of systole (r = 0.99) and also the end-systolic LVP but underestimated LVP during midsystole by 48 +/- 5 (SD) mmHg (P less than 0.05). When a pressure-dependent source resistance (K = 0.0015 s/ml) was added to the model to reduce LVP in proportion to Q, such that P(t) = E(t) [V(t)-Vo] X [1 - KQ]), LVP during the isovolumic beat was accurately predicted throughout systole (r = 0.99). However, the time to develop peak isovolumic pressure was 22 +/- 7 ms less than predicted. Similar results were obtained during inotropic stimulation with dobutamine in five animals.

RECENT PROGRESS ON GaN-BASED ELECTRON DEVICES

2006 ◽  
Vol 16 (02) ◽  
pp. 469-477
Author(s):  
Yasuhiro Uemoto ◽  
Yutaka Hirose ◽  
Tomohiro Murata ◽  
Hidetoshi Ishida ◽  
Masahiro Hikita ◽  
...  
Keyword(s):  
Noise Figure ◽  
Field Effect Transistors ◽  
Drain Current ◽  
Low Noise ◽  
60 Ghz ◽  
Si Doping ◽  
Power Handling Capability ◽  
Source Resistance ◽  
State Breakdown ◽  
A Current

We present results of some novel AlGaN/GaN heterojunction field-effect transistors (HFETs) specifically developed for RF front-end and power applications. To reduce the parasitic resistance, two unique techniques: selective Si doping into contact area and a superlattice (SL) cap structure, are developed. With the selective Si doping method, a transistor with an on-state resistance as low as 1.86 Ω·mm and a Tx/Rx switch IC with very low insertion loss (0.26 dB) and very high power handling capability (P1dB over 40 dBm) were obtained. With the SL cap HFETs, an ultra low source resistance of 0.4 Ω·mm was achieved and excellent DC and RF performances were demonstrated. The typical characteristics of these HFETs are: maximum transconductance of over 400 mS/mm, maximum drain current of 1.2 A/mm, cut-off frequency of 60 GHz, maximum oscillation frequency of 140 GHz, and a very low noise figure of 0.7 dB with 15 dB gain at 12 GHz. For power applications, in order to significantly reduce fabrication cost, we fabricated the AlGaN/GaN HFET on a conductive Si substrate with a source-via grounding (SVG) structure. The device has a very low on-state sheet resistance of 1.9 mΩ·cm2, a high off-state breakdown voltage of 350 V, and a current handling capability of 150 A. In addition, a sub-nano second switching response with t r of 98 ps and t f of 96 ps with a current density as high as 2.0 kA/cm2 is demonstrated for the first time.

scholarly journals CRITERIA AND SELECTION PROCEDURE OF VIDEO MATERIALS FOR BUILDING PRE-SERVICE FOOD TECHNOLOGISTS’ SPEECH PRODUCTION COMPETENCE

World Science ◽  
2020 ◽  
Vol 2 (2(54)) ◽  
pp. 13-17
Author(s):  
Anna Boyko
Keyword(s):  
Speech Production ◽  
Selection Criteria ◽  
Selection Procedure ◽  
Materials Selection ◽  
Selection For ◽  
Definition Of

The article describes the process of video materials’ criteria selection for building pre-service food technologist’s speech production competence and the procedure of video materials selection according to these criteria. The article defines the definition of selection criteria and determines factors were considered in the process of video materials’ selection criteria specification.

scholarly journals Study of Analog/Rf and Stability Investigation of Surrounded Gate Junctionless Graded Channel MOSFET(SJLGC MOSFET)

2021 ◽  
Author(s):  
Sarita Misra ◽  
Sudhansu Mohan Biswal ◽  
Biswajit Baral ◽  
Sanjit Kumar Swain ◽  
Sudhansu Kumar Pati
Keyword(s):  
Drain Current ◽  
Rf Circuits ◽  
Superior Performance ◽  
Threshold Region ◽  
Lateral Direction ◽  
Subthreshold Region ◽  
Digital Switching ◽  
Rf Performance ◽  
The Impact ◽  
Rf Performances

Abstract This paper explores the potential advantage of surrounded gate junctionless graded channel (SJLGC) MOSFET in the view of its Analog, RF performances using ATLAS TCAD device simulator. The impact of graded channel in the lateral direction on the potential, electric field, and velocity of carriers, energy band along the channel is investigated systematically. The present work mainly emphasises on the superior performance of SJLGC MOSFET by showing higher drain current (ID) , transconductance (gm) ,cut off frequency (fT) , maximum frequency of oscillation (fmax) , critical frequency (fK) .The drain current is improved by 10.03 % in SJLGC MOSFET due to the impact of grading the channel. There is an improvement in fT, fmax, fK by 45%, 29% and 18% respectively in SJLGC MOSFET showing better RF Performance. The dominance of the SJLGC MOSFET over SJL MOSFET is further elucidated by showing 74% improvement in intrinsic voltage gain (gm / gds) indicating its better applications in sub threshold region. But the transconductance generation factor of SJLGC MOSFET is less than SJL MOSFET in the subthreshold region. The intrinsic gate delay (ζD) of SJLGC MOSFET is less in comparison to SJL MOSFET due to the impact of lower gate to gate capacitance (CGG) suggesting better digital switching applications. The simulation results reveal that SJLGC MOSFET can be a competitive contender for the coming generation of RF circuits covering a broad range of operating frequencies in RF spectrum.

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