Search

In this paper an in – depth analysis of SiN passivated AlGaN/GaN HEMTs on sapphire and SiC substrate for radiation hardened operation has been presented. An exhaustive study comprising of Conventional, Gate Field Plate (GFP), and Dual Field Plate (DFP) architectures have been studied through exhaustive TCAD simulations under different radiation environments. Initial analysis has been carried out by intentionally subjecting the devices to heavy ion particle strikes. The particle strikes have also been localized along different positions of the device in order to examine the behavior of the architectures due to the occurrence of Single Event Effects (SEEs) in the space environment. Comparisons demonstrate an excellent reliability of DFP HEMTs in terms of resistance to the change observed in device performance parameters post heavy ion strike. The reliability of the device architectures has also been investigated in presence of proton shower by creating a virtual environment comprising of energetic protons. Due to non – ionizing energy loss (NIEL), the protons can traverse large distances in the epi – layer stack. In this regard, Substrate dependent effects have also been investigated by coupling the AlGaN/GaN stack over SiC-4 H and Sapphire substrates to study the robustness against the heavy ion and proton flux. Significant enhancement in both the OFF – State and ON – State current has been observed on the SiC-4 H substrate, indicating a robust operation for GaN on Sapphire substrates. The radiation hardness of the device architectures has also been studied by realizing thick AlGaN barriers that further improve the device performance. Finally, the device architectures are compared from an application perspective by investigating the Class AB Power Amplifier performance. Comparisons demonstrate the suitability of DFP AlGaN/GaN HEMTs in achieving both robustness against different radiation environments and as well as exhibiting higher output power density compared to its Conventional and GFP counterparts. [ABSTRACT FROM AUTHOR]

This investigation examines the performance of AlGaN/GaN MISHEMTs having single-gate and dual-gate with different biasing combinations to explore the linearity in terms of gmpeak, gate voltage swing (GVS) and higher-order coefficients for intermodulation distortion for low-noise amplifiers (LNAs). In addition, the influence of distinct gate biasing configurations of DG-MISHEMT on current collapse (CC) (in response to OFF-state stress in drain) has been studied using TCAD simulations. It has been observed that drop in drain current value after the gate–drain voltages return to quiescent voltages (VGSQ, VDSQ) reduces for DG-MISHEMT (when both the gates are shorted together) to 9.1% as compared with 19.4% for SG-MISHEMT. Besides, the CC phenomena for DG-MISHEMTs (for shorted gates) exhibit a slight increase from 9% to 11.8% when workfunction increases from 4.1 eV to 5.2 eV for gate G2. Further, linearity in terms of GVS is observed to be doubled for AlGaN/GaN DG-MISHEMTs with both the gates connected together as compared with device with screen gate G2 shorted to source. Additionally, radio frequency performance has been studied in terms of cut-off frequencies fT and fmax and minimum noise-figure NFmin for AlGaN/GaN SG-MISHEMT and DG-MISHEMTs for different gate to gate distance i.e., LGG =100 and 200 nm. It is observed that NFmin is minimum for AlGaN/GaN DG-MISHEMT (with gate G1 floating and gate G2 is biased and LGG =100 nm) i.e., 1.13 dB with corresponding power gain of 18.7 dB at 50 GHz. [ABSTRACT FROM AUTHOR]

ATLAS TCAD-based comparative investigation (mainly breakdown voltage, cut-off frequency and leakage current) has been presented in this work for different length of gate field plate and source field plate. 127 V of breakdown voltage has been achieved at 0.25 µm gate length having 0.8 µm gate field plate length and 1 µm source field plate length. By amalgamating source field plate, maximum cut-off frequency of 38 GHz was achieved at 0.25 µm channel length. Passivation layer permittivity and barrier thickness has also been used to optimize the device performance. The improvement in breakdown voltage is less prominent than the deterioration in cut-off frequency with the enhancement in passivation layer permittivity. Leakage current of source field plate HEMT has also been studied for different passivation layer permittivity. [ABSTRACT FROM AUTHOR]

TCAD-based numerical investigation of RingFET has been presented in this paper for the detection of gas molecules. Sensitivity of the device has been assessed by calculating the change in off-state current with the change in gate work-function (which changes due to the presence of gas molecule). The behavior of the device has also been compared with the equivalent bulk MOSFET and it was observed that RingFET architecture shows 23% higher sensitivity against gas molecules than equivalent bulk MOSFET. Also, the degradation in device sensitivity with applied drain bias is higher in bulk MOSFET. Optimization in the sensitivity parameter has been done by using different channel materials like GaN, InGaN, and GaAs. Compared to GaAs and silicon, GaN-based RingFET is more sensitive towards gas molecules in the sub-threshold region (due to the wider band gap) besides having lower drain current than GaAs and silicon-based RingFET. [ABSTRACT FROM AUTHOR]

This paper examines the DC performance of Dual-Gate MISHEMT with different substrate material such as sapphire, silicon carbide SiC, and silicon. The performance parameters evaluated are threshold voltage, drain current, transconductance, and drain conductance. It is observed that DG-MISHEMT with the sapphire substrate and HfO2 gate dielectric results in positive threshold voltage shift from −4.7 to −3.8 V(∼19%) and also degrades the drain current as compared to the device with silicon nitride gate dielectric due to the reduced channel charge concentration. But the device with HfO2/Al2O3 gate stack maintains 182 mA/mm of IDS along with a positive threshold voltage shift of 14.8% as compared to DG-MISHEMT with Si3N4 gate dielectric and sapphire substrate. A similar performance has been observed with Dual-Gate MISHEMT with SiC and silicon substrate. The device, having the silicon substrate and HfO2/Al2O3 gate stack, shows a positive threshold voltage shift of ∼53%, but as a trade-off the drain current reduces to 158 mA/mm as compared to 183 mA/mm of the device at low drain bias with the sapphire substrate and Si3N4 gate dielectric. [ABSTRACT FROM AUTHOR]

In this work, a gate underlap channel dielectric-modulated (DM) double-gate (DG) MOSFET which is working as biosensor for the label free electrical detection of the biomolecules has been investigated. The electrical characteristics such as, threshold voltage and drain current of DM DG MOSFET have been studied by the device simulation. The shift in the threshold voltage has been used as the sensing metric to detect the sensitivity after the biomolecules interacts with the device. four-gate NMOS inverter has also been used to investigate a label free electrical detection of the biomolecules. The work has been done under the consideration of dry environment condition. [ABSTRACT FROM AUTHOR]

In this paper, an analytical model has been developed for a split gate junctionless (JL) MOSFET, which works as a bio-transistor to detect the analytes (biomolecules), such as protein, DNA, enzyme, cell, and so on, using the dielectric-modulation technique. We have also studied the neutralization of charged analytes when charge reduction due to drying out. The analytical model has been investigated by solving 2-D Poisson’s equation. For the validation of analytical results, a split gate JL MOSFET has been virtually fabricated through sprocess and the electrostatic properties of device simulated by sdevice tools of the “Sentaurus” device simulator. For the bio-species immobilization, an underlap region also known as open cavity is formed in the device through etching oxide material and gate material from the middle of the channel. The electrostatic properties of device, such as surface potential, threshold voltage, drain current, and sensitivity, get affected by the immobilization of analytes at the SiO2 layer (which acts as an adhesion layer in the cavity region). The change in the threshold voltage and transfer characteristics of the device is pondered as the sensing metric to detect the bio-targets under dry environment. [ABSTRACT FROM PUBLISHER]

• Reliability aspect of the SFP-MISHEMT under the linearity and SEU environment have been demonstrated. • Temperature related degradation has also been explored and the results have been investigated with varying device parameters. • Compared to conventional MISHEMT, SFP-MISHEMT shows better linearity in terms of higher VIP 2 , IIP 3 and lower intermodulation distortion. • The influence of process variability has also been studied. • Improved reliability in terms of the lesser SEU generated effects has been observed from the SFP-MISHEMT. In this work, the reliability of Slant Field Plate SFP-MISHEMT has been discussed using linearity and Single Event Upset parameters for millimeter wave (mmW) applications in outer space environment. The influence of process variability on the RF and linearity parameters of SFP-MISHEMT like g m ' and g m ", higher VIP 2 , IIP 3 and IMD 3 has also been explored. For analyzing the SEU behavior, three different positions of the ion strike have been used and the investigation has been conducted with varying energy and device parameters like temperature. The impact of the gate to drain length (L gd) and oxide permittivity and gate length (varied from 60 nm to 210 nm keeping the length of the SFP constant as 20 nm (on both side)) on the device sensitivity has also been explored. Improved reliability in terms of the lesser SEU generated effects has also been observed from the SFP-MISHEMT in contrast with C-MISHEMT. [ABSTRACT FROM AUTHOR]

In this paper, an analytical model for Junctionless (JL) Metal–Oxide–Semiconductor Field-Effect Transistor (MOSFET) based biosensor for label free electrical detection of biomolecules like enzyme, cell, DNA etc. using the Dielectric Modulation (DM) technique has been developed. The analytical results are validated with the help of “Sentaurus” device simulation software. For the biomolecule immobilization, nanogap cavity is formed in the JL MOSFET by etching gate oxide layer from both source as well as drain end of the channel. As a result, the surface potential in the channel underneath the nanogap cavity region is affected by the neutral and charged biomolecules that binds to SiO 2 adhesion layer in the cavity. The surface potential solution is obtained by solving a 2-D Poisson’s equation assuming parabolic potential profile in the channel. The shift in threshold voltage and drain current of the device has been considered as the sensing metric for detection of biomolecules under dry environment condition. [ABSTRACT FROM AUTHOR]

This work presents a systematic study to achieve the best result of having high breakdown voltage with high-frequency operation for a 150 nm GaN HEMT device (fabricated) using different field plate engineering techniques. The device breakdown voltage, cut-off frequency and maximum frequency should be high for high power and high frequency applications. The conventional device has a lower breakdown voltage but good cut-off and maximum frequency ranges. Field plate engineering has been done for breakdown improvement. However, the device's frequency operation is hampered by the typical source and gate field plate. As a result, an Air bridge source connected field plate and floating gate field plate architectures are explored and investigated. The best outcome is obtained with air bridge source connected field plate with V BOff = 100 V maintaining the cut-off frequency and maximum frequency at 29.8 GHz and 50.3 GHz respectively which is suitable for high power and high frequency applications. • Systematic study to achieve high V BOff with high-frequency operation for a 150nm GaN HEMT device using field plate engineering techniques. • The conventional device has a lower breakdown voltage but good cut-off and maximum frequency ranges. • Field plate engineering has been done for breakdown improvement. • However, the device's frequency operation is hampered by the typical source and gate field plate. • An Air bridge source connected field plate and floating gate field plate architectures are explored. • The best outcome is obtained with air bridge source connected field plate. • It has V BOff =100 V maintaining the cut-off frequency and maximum frequency at 29.8 GHz and 50.3 GHz respectively. • It is suitable for high power and high frequency applications. [ABSTRACT FROM AUTHOR]

This article investigates the incorporation of field plates in AlGaN/GaN High Electron Mobility Transistors (HEMTs) which leading to enhancement in the device breakdown voltage and a reduction in the reverse leakage current. Using Atlas TCAD software breakdown behavior of gate-connected field plate (GFP), gate-source (dual) field plate, and discrete source-connected field plate (Sunken SC-FP) designs with field plate length variation is probed and physical insight is developed through electric field profile, and impact ionization contour plots. By employing a Sunken SC-FP with gate length of 0.4 μm in the gate-drain access region the device breakdown voltage is improved and has high JFOM (4.8 THz·V). Also, on-resistance (R ON) degradation is minimum in the Sunken SCFP (20.12 %), compared with GFP (31.20 %) and dual FP (24.96 %) architectures, when the device is stressed in the off-state (VGS = −40 V) for 1 min. The RF performance of the Sunken SC-FP HEMT is studied using small signal parameters and the load pull measurements as a function of drain bias. • This work investigates the Discrete Source connected Field Plate (DSC – FP) AlGaN/GaN HEMT for high power applications. • TCAD study is presented based on home – grown conventional architecture which is further used to optimize the DSC – FP HEMT. • DSC – FP HEMT exhibits f T comparable to the conventional counterpart while boosting the breakdown voltage by 5 times. • The optimized DSC – FP HEMT is fabricated and exhibits a P OUT of 9.2 W/mm at 3 GHz. • The reliability of the DSC – FP HEMT is investigated by subjecting the fabricated devices to a high field electrical stress. [ABSTRACT FROM AUTHOR]

In this work, the sensitivity of two types gate underlap Junctionless Double Gate Metal-Oxide-Semiconductor Field-Effect Transistor (JL DG MOSFET) has been compared when the analytes bind in the underlap region. Gate underlap region considered at source end and drain end once at a time in the channel of JL DG MOSFET. Separate models have been derived for both types of gate underlap JL DG MOSFETs and verified through device simulation TCAD tool sprocess and sdevice. To detect the bio-molecules, Dielectric Modulation technique has been used. The shift in the threshold voltage has been pondered as the sensing parameter to detect the presence of biomolecules when they are bound in gate underlap channel region of the devices. [ABSTRACT FROM AUTHOR]