Optimization of InAlAs/InGaAs HEMT Performance for Microwave Frequency Applications and Reliability

Ritesh Gupta,Sandeep Kumar Aggarwal,Mridula Gupta,R.S.Gupta 대한전자공학회 2004 Journal of semiconductor technology and science Vol.4 No.3

In the present paper efforts have been made to optimize InALs/lnGaAs HEMT by enhancing the effective gate voltage (Vo-Voft) using pulsed doped structure from uniformly doped to delta doped for microwave frequency applications and reliability. The detailed design criteria to select the proper design parameters have also been discussed in detail to exclude parallel conduction without affecting the dewice performance. Then the optimized value of Vo-Voft and breakdown voltages corresponding to maximum value of transconductance has been obtained. These values are then used to predict the transconductance and cut-off frequency of the device for different channel depths and gate lengths.<br/> Index Terms-InAlAs/InGaAs heterostructure, delta doped, uniformly doped, pulsed doped, parallel conduction, channel confinement and breakdown, woltage<br/>

Analytical Model for Metal Insulator Semiconductor High Electron Mobility Transistor (MISHEMT) for its High Frequency and High Power Applications

Ritesh Gupta,Sandeep Kr Aggarwal,Mridula Gupta,R. S. Gupta 대한전자공학회 2006 Journal of semiconductor technology and science Vol.6 No.3

A new analytical model has been proposed for predicting the sheet carrier density of Metal insulator Semiconductor High Electron Mobility Transistor (MISHEMT). The model takes into account the non-linear relationship between sheet carrier density and quasi Fermi energy level to consider the quantum effects and to validate it from subthreshold region to high conduction region. Then model has been formulated in such a way that it is applicable to MESFET/HEMT/MISFET with few adjustable parameters. The model can also be used to evaluate the characteristics for different gate insulator geometries like T-gate etc. The model has been extended to forecast the drain current, conductance and high frequency performance. The results so obtained from the analysis show excellent agreement with previous models and simulated results that proves the validity of our model.

Analytical Model for Metal Insulator Semiconductor High Electron Mobility Transistor (MISHEMT) for its High Frequency and High Power Applications

Gupta, Ritesh,Aggarwal, Sandeep Kr,Gupta, Mridula,Gupta, R.S. The Institute of Electronics and Information Engin 2006 Journal of semiconductor technology and science Vol.6 No.3

A new analytical model has been proposed for predicting the sheet carrier density of Metal insulator Semiconductor High Electron Mobility Transistor (MISHEMT). The model takes into account the non-linear relationship between sheet carrier density and quasi Fermi energy level to consider the quantum effects and to validate it from subthreshold region to high conduction region. Then model has been formulated in such a way that it is applicable to MESFET/HEMT/MISFET with few adjustable parameters. The model can also be used to evaluate the characteristics for different gate insulator geometries like T-gate etc. The model has been extended to forecast the drain current, conductance and high frequency performance. The results so obtained from the analysis show excellent agreement with previous models and simulated results that proves the validity of our model.

Optimization of InAlAs/InGaAs HEMT Performance for Microwave Frequency Applications and Reliability

Gupta, Ritesh,Aggarwal, Sandeep Kumar,Gupta, Mridula,Gupta, R.S. The Institute of Electronics and Information Engin 2004 Journal of semiconductor technology and science Vol.4 No.3

In the present paper efforts have been made to optimize InAlAs/InGaAs HEMT by enhancing the effective gate voltage ($(V_c-V_off)$) using pulsed doped structure from uniformly doped to delta doped for microwave frequency applications and reliability. The detailed design criteria to select the proper design parameters have also been discussed in detail to exclude parallel conduction without affecting the del ice performance. Then the optimized value of $V_c-V_off$and breakdown voltages corresponding to maximum value of transconductance has been obtained. These values are then used to predict the transconductance and cut-off frequency of the del ice for different channel depths and gate lengths.

Short Channel Analytical Model for High Electron Mobility Transistor to Obtain Higher Cut-Off Frequency Maintaining the Reliability of the Device

Gupta, Ritesh,Aggarwal, Sandeep Kumar,Gupta, Mridula,Gupta, R.S. The Institute of Electronics and Information Engin 2007 Journal of semiconductor technology and science Vol.7 No.2

A comprehensive short channel analytical model has been proposed for High Electron Mobility Transistor (HEMT) to obtain higher cut-off frequency maintaining the reliability of the device. The model has been proposed to consider generalized doping variation in the directions perpendicular to and along the channel. The effect of field plates and different gate-insulator geometry (T-gate, etc) have been considered by dividing the area between gate and the high band gap semiconductor into different regions along the channel having different insulator and metal combinations of different thicknesses and work function with the possibility that metal is in direct contact with the high band gap semiconductor. The variation obtained by gate-insulator geometry and field plates in the field and channel potential can be produced by varying doping concentration, metal work-function and gate-stack structures along the channel. The results so obtained for normal device structure have been compared with previous proposed model and numerical method (finite difference method) to prove the validity of the model.

Metal Insulator Gate Geometric HEMT: Novel Attributes and Design Consideration for High Speed Analog Applications

Ritesh Gupta,Ravneet Kaur,Sandeep Kr Aggarwal,Mridula Gupta,R. S. Gupta 대한전자공학회 2010 Journal of semiconductor technology and science Vol.10 No.1

Improvement in breakdown voltage (BVds) and speed of the device are the key issues among the researchers for enhancing the performance of HEMT. Increased speed of the device aspires for shortened gate length (Lg), but due to lithographic limitation, shortening Lg below sub-micrometer requires the inclusion of various metal-insulator geometries like T-gate on to the conventional architecture. It has been observed that the speed of the device can be enhanced by minimizing the effect of upper gate electrode on device characteristics, whereas increase in the BVds of the device can be achieved by considering the finite effect of the upper gate electrode. Further, improvement in BVds can be obtained by applying field plates, especially at the drain side. The important parameters affecting BVds and cut-off frequency (fT) of the device are the length, thickness, position and shape of metal-insulator geometry. In this context, intensive simulation work with analytical analysis has been carried out to study the effect of variation in length, thickness and position of the insulator under the gate for various metal-insulator gate geometries like T-gate, Γ-gate, Step-gate etc., to anticipate superior device performance in conventional HEMT structure.

Metal Insulator Gate Geometric HEMT: Novel Attributes and Design Consideration for High Speed Analog Applications

Gupta, Ritesh,Kaur, Ravneet,Aggarwal, Sandeep Kr,Gupta, Mridula,Gupta, R.S. The Institute of Electronics and Information Engin 2010 Journal of semiconductor technology and science Vol.10 No.1

Improvement in breakdown voltage ($BV_{ds}$) and speed of the device are the key issues among the researchers for enhancing the performance of HEMT. Increased speed of the device aspires for shortened gate length ($L_g$), but due to lithographic limitation, shortening $L_g$ below sub-micrometer requires the inclusion of various metal-insulator geometries like T-gate onto the conventional architecture. It has been observed that the speed of the device can be enhanced by minimizing the effect of upper gate electrode on device characteristics, whereas increase in the $BV_{ds}$ of the device can be achieved by considering the finite effect of the upper gate electrode. Further, improvement in $BV_{ds}$ can be obtained by applying field plates, especially at the drain side. The important parameters affecting $BV_{ds}$ and cut-off frequency ($f_T$) of the device are the length, thickness, position and shape of metal-insulator geometry. In this context, intensive simulation work with analytical analysis has been carried out to study the effect of variation in length, thickness and position of the insulator under the gate for various metal-insulator gate geometries like T-gate, $\Gamma$-gate, Step-gate etc., to anticipate superior device performance in conventional HEMT structure.

Genetic Structure and Differentiation of Three Indian Goat Breeds

Dixit, S.P.,Verma, N.K.,Aggarwal, R.A.K.,Kumar, Sandeep,Chander, Ramesh,Vyas, M.K.,Singh, K.P. Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.9

Gene flow, genetic structure and differentiation of Kutchi, Mehsana and Sirohi breeds of goat from North-Western India were evaluated based on 25 microsatellite markers so as to support breed conservation and improvement decisions. The microsatellite genotyping was carried out using an automated DNA sequencer. The gene diversity across the studied loci for the Kutchi breed varied from 0.57 (ILST 065) to 0.93 (OarFCB 304, OMHC 1, ILSTS 058) with an overall mean of 0.79${\pm}$0.02. The corresponding values for Mehsana and Sirohi breeds were 0.16 (ILST 008) to 0.93 (OMHC 1, ILSTS 058) with an average of 0.76${\pm}$0.04, and 0.50 (ILSTS 029) to 0.94 (ILSTS 058) with an average of 0.78${\pm}$0.02, respectively. The Mehsana breed had lowest gene diversity among the 3 breeds studied. All the populations showed an overall significant heterozygote deficit ($F_{is}$). The Fis values were 0.26, 0.14 and 0.36 for Kutchi, Mehsana and Sirohi goat breeds, respectively. Kutchi and Mehsana were more differentiated (16%) followed by Mehsana and Sirohi (13%).The measures of standard genetic distance between pairs of breeds indicated that the lowest genetic distance was between Kutchi and Sirohi breeds (0.73) and the largest genetic distance was between Mehsana and Kutchi (1.0) followed by Sirohi and Mehsana (0.75) breeds. Mehsana and Kutchi are distinct breeds and this was revealed by the estimated genetic distance between them. All measures of genetic variation revealed substantial genetic variation in each of the populations studied, thereby showing good scope for their further improvement.

Study of Serum Adipocytokines and Their Association with Insulin Sensitivity in Morbidly Obese Individuals Undergoing Bariatric Surgery

Astha Sachan,Archna Singh,Sakshi Shukla,Sandeep Aggarwal,Ishfaq Mir,Rakhee Yadav 대한비만학회 2020 The Korean journal of obesity Vol.29 No.4

Background: Obese adipose tissue secretes a variety of adipocytokines that act as metabolic regulators with complex mechanisms. Our objective was to compare serum concentration of a panel of adipocytokines between obese and non-obese individuals and identify any distinct patterns correlating with insulin sensitivity in obesity. Methods: We designed a cross-sectional study among obese (body mass index [BMI] ≥30 kg/m2, n=62) and non-obese (BMI <25 kg/m2, n=32) individuals to compare circulating levels of the adipokines, such as adiponectin and resistin in conjunction with the measurement of the levels of inflammatory cytokines including C-reactive protein (CRP), interleukin (IL)-6, IL-8, monocyte chemoattractant protein (MCP)-1, and tumor necrosis factor (TNF)-α using Luminex multiplex immunoassay with drop array technology. Correlations between circulating adipocytokine levels and those of multiple well-established markers of insulin resistance including homeostatic model assessment of insulin resistance (HOMA-IR), homeostatic model assessment of β-cell function (HOMA-β) and quantitative insulin sensitivity check index were also established. Results: CRP, IL-8, MCP-1, and TNF-α levels were higher in obese than non-obese individuals; the CRP and IL-8 differences were statistically significant. CRP correlated significantly with markers of insulin resistance (fasting plasma insulin, HOMA-IR, and QUICKI), and adiponectin correlated with HOMA-β in obese individuals. We divided the group of obese individuals on the basis of HOMA-IR levels into insulin-resistant (IR; HOMA-IR ≥2.5) and insulin-sensitive (IS; HOMA-IR <2.5) groups; and 43 out of 62 participants were IR despite comparable BMIs. An overall proinflammatory profile was compared between IR and IS obese, though the values were higher in IR obese but the difference was not significant. Conclusion: Obesity is associated with a general inflammatory milieu and a crosstalk between adipocytokines and insulin resistance is complex as well as multifactorial.

Review on metallic components released due to the use of electronic cigarettes

Vinit K. Mishra,Ki-Hyun Kim,Pallabi Samaddar,Sandeep Kumar,M. L. Aggarwal,K. M. Chacko 대한환경공학회 2017 Environmental Engineering Research Vol.22 No.2

The use of electronic cigarettes (ECs) is recognized as a source of many pollutants, just like conventional cigarettes (CCs). The analysis of EC aerosol samples has confirmed the presence of various metallic species. Most of these metals originate from various parts of the cartomizer, e.g., solder joints, wires, and silicate beads. The metal concentration levels in EC samples were shown to be generally two to four orders of magnitude lower than those of CCs. However, the use of ECs can still pose significant human health hazards as consumers are exposed to the toxicity of those metals and many other hazardous pollutants released simultaneously via the vaping of ECs. The review also describes the detection and quantification of various metals in ECs and CCs. This review was carried out to assess the level of metal species released from ECs and to suggest proper guidelines to control consumer exposure.