Confined Energy State Based Hypothetical Observations about Device Parameters of AlGaN / GaN HEMT

In this paper, the gate threshold voltage of AlGaN / GaN HEMT devices has been analytically predicted based on the calculated energy levels inside triangular quantum well at the hetero-interface and found to be comparable with experimental data. The conceptual explanation of device linearity in large signal applications has been presented in terms of quantized energy levels in the quantum well. The dependence of threshold voltage and linear operable gate voltage range on a newly introduced parameter named “Surface Factor” is analyzed as well

Gate leakage current reduction with advancement of graded barrier AlGaN/GaN HEMT

The gate leakage current reduction solution of AlGaN/GaN HEMT device issue has been addressed in this paper with compositional grading of AlGaN barrier layer. This work is also conjugated with the critical thickness limitation of heterostructure material growth. Hence, critical thickness calculation of AlGaN over GaN has been kept in special view. 1D Schrodinger and Poisson solver was used to calculate the 2DEG concentration and effective location to use it in the ATLAS device simulator for the predictions. The proposed Al0.50Ga0.50N/Al0.35Ga0.65N /Al0.20Ga0.80N/GaN HEMT structure exhibits the leakage current of the order of around 15 nA/mm at gate voltage of 1 V. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2789

Confined Energy State Based Hypothetical Observations about Device Parameters of AlGaN / GaN HEMT

In this paper, the gate threshold voltage of AlGaN / GaN HEMT devices has been analytically predicted based on the calculated energy levels inside triangular quantum well at the hetero-interface and found to be comparable with experimental data. The conceptual explanation of device linearity in large signal applications has been presented in terms of quantized energy levels in the quantum well. The dependence of threshold voltage and linear operable gate voltage range on a newly introduced parameter named “Surface Factor” is analyzed as well

Developmental Impact Analysis of an ICT-Enabled Scalable Healthcare Model in BRICS Economies

This article highlights the need for initiating a healthcare business model in a grassroots, emerging-nation context. This article’s backdrop is a history of chronic anomalies afflicting the healthcare sector in India and similarly placed BRICS nations. In these countries, a significant percentage of populations remain deprived of basic healthcare facilities and emergency services. Community (primary care) services are being offered by public and private stakeholders as a panacea to the problem. Yet, there is an urgent need for specialized (tertiary care) services at all levels. As a response to this challenge, an all-inclusive health-exchange system (HES) model, which utilizes information communication technology (ICT) to provide solutions in rural India, has been developed. The uniqueness of the model lies in its innovative hub-and-spoke architecture and its emphasis on affordability, accessibility, and availability to the masses. This article describes a developmental impact analysis (DIA) that was used to assess the impact of this model. The article contributes to the knowledge base of readers by making them aware of the healthcare challenges emerging nations are facing and ways to mitigate those challenges using entrepreneurial solutions

A Strategic Review on Growth of InP on Silicon Substrate for Applications in High Frequency RF Devices

A review is presented on the advances in InAlAs/InGaAs High Electron Mobility transistors (HEMT) on silicon substrates for high frequency and low noise applications. Although InAlAs/InGaAs HEMTs on InP and GaAs substrates have been much appreciated due to their superior performance, their widespread applications have been hindered due to higher cost of the substrates. Silicon has been used as an alternative substrate considering the benefits of low cost, technological maturity and integration of III-V and silicon technology inspite of the constraints like lattice mismatch and large difference in thermal expansion coefficient

New evolving directions for device performance optimization based integration of compound semiconductor devices on silicon

Rapid advances in Compound Semiconductor (CS) technologies over last several decades have lead to high performances in peak power, power added efficiency (PAE) and linearity, but these devices are not amenable for integration on mainstream silicon technologies. A strategic direction has been presented for the growth of CS devices on silicon with challenges abounding in scalability, compatibility and cost effectiveness while extracting optimized device performances. The approach at IIT Kharagpur has been simulation and experimental development of customized metamorphic buffers that are scalable and compatible to silicon without sacrificing any CS performances, primarily for electronic applications. This has evolved into a new strategic paradigm for performance optimization of seemingly competing and disparate properties which otherwise will not be supported by conventional process technologies. Simulation of these next generation structures reveals assimilation of superior device properties, with a novel five Indium content composite channel MHEMT indicating improvements over existing composite channel MHEMT in terms of linearity and higher current performances. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2793

Strategic review of arsenide, phosphide and nitride mosfets

Metal oxide semiconductor field effect transistor used as an amplifier and switch uses Si primarily as a channel material for its very stable oxide SiO2. In-spite of many advantages there are some restrictions for Si MOS, so the world is approaching towards compound semiconductor for higher frequency and current. The development of compound semiconductor metal oxide semiconductor is also facing critical problems due to the lack of availability of proper gate oxide material. Research is being conducted on arsenide and phosphide metal oxide semiconductor field effect transistor. Nitride channel MOS are in focus due to their high band gap, high current and high temperature uses. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2208

Growth and characterization of indium gallium phosphide on gallium arsenide by gas-source molecular beam epitaxy system and its applications to heterostructures

InGaP/GaAs system presents an attractive alternative to GaAs/AlGaAs system for heterojunction devices because of its unique heterojunction properties, wide band gap of about 1.90 eV for the lattice matched composition and absence of oxidation problems typical for AlGaAs. However, the growth of InGaP requires the use of phosphine, which necessitated the use of Gas Source Molecular Beam Epitaxy (GSMBE). The gases involved are very hazardous, extremely toxic, highly inflammable and explosive at elevated temperatures. Adequate care has been taken for the safe use of these gases so that this attractive technique is properly utilized. The GSMBE system is equipped with a central alarm command system with audio-visual alarms for a variety of monitored conditions and interlocks for automatic shutdown.Samples studied were grown on (100) GaAs substrates under various growth conditions. Reproducible growth conditions have been established with respect to optimisation of pressure and temperature so as to achieve good material properties. Structural characterization using X ray has been carried out for the determination of material composition and evaluation of crystal quality. Very narrow full width at half maxima values indicated good crystal quality. Additionally, cross-sectional TEM has shown smooth heterointerface. Subsequent to this, good hall mobility at room temperature and at 77K, confirmed the material quality. Photoluminescence has been utilized for the evaluation of the E\sb0 gap. The PL exhibited very narrow full width at half maxima for lattice matched composition. Apart from evaluation of the E\sb1 gap, spectroscopic ellipsometry has been used to investigate the compositional dependence of the E\sb1 gap (and its broadening).P-type modulation doped heterostructures has been implemented using InGaP/GaAs, demonstrating two dimensional hole gas (2DHG) with good p-type hole mobilities measured from room temperature up to very low temperatures. The approximate constant value of mobility in the low temperature region strongly confirms the presence of 2DHG. A simple model has been formulated for the estimation of valence band discontinuity from the measured 2DHG data at cryogenic temperatures. Heterostructure Bipolar Transistor has been demonstrated using InGaP/GaAs system with the realisation of good current gain and low offset voltages. The double heterostructure bipolar transistor showed even smaller offset voltages. The classical V\sb{CE} versus I\sb{c} plots and gummel plots for the devices shows an ideality factor close to unity for I\sb{c} and other usual characteristic features.U of I OnlyETDs are only available to UIUC Users without author permissio

Impact of varying buffer thickness generated strain and threading dislocations on the formation of plasma assisted MBE grown ultra-thin AlGaN/GaN heterostructure on silicon

Plasma-assisted molecular beam epitaxy (PAMBE) growth of ultra-thin Al0.2Ga0.8N/GaN heterostructures on Si(111) substrate with three buffer thickness (600 nm/400 nm/200 nm) have been reported. An unique growth process has been developed that supports lower temperature epitaxy of GaN buffer which minimizes thermally generated tensile strain through appropriate nitridation and AlN initiated epitaxy for achieving high quality GaN buffer which supports such ultra-thin heterostructures in the range of 10-15Å. It is followed by investigations of role of buffer thickness on formation of ultra-thin Al0.2Ga0.8N/GaN heterostructure, in terms of stress-strain and threading dislocation (TD). Structural characterization were performed by High-Resolution X-Ray Diffraction (HRXRD), room-temperature Photoluminescence (RT-PL), High Resolution Transmission Electron Microscopy (HRTEM) and Atomic Force Microscopy (AFM). Analysis revealed increasing biaxial tensile stress of 0.6918 ± 0.04, 1.1084, 1.1814 GPa in heterostructures with decreasing buffer thickness of 600, 400, 200 nm respectively which are summed up with residual tensile strain causing red-shift in RT-PL peak. Also, increasing buffer thickness drastically reduced TD density from the order 1010 cm−2 to 108 cm−2. Surface morphology through AFM leads to decrease of pits and root mean square value with increasing buffer thickness which are resulted due to reduction of combined effect of strain and TDs