Umesh K. Mishra
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View article: MOCVD Growth of Relaxed, Crack-Free AlGaN on Tiled GaN Substrates
MOCVD Growth of Relaxed, Crack-Free AlGaN on Tiled GaN Substrates Open
AlxGa1-xN layers with up to 53% Al composition and 1.3 µm total thicknesses were grown utilizing step-graded layers on dense arrays of 10 × 10 µm2 GaN tiles. While the layers were fully relaxed and crack-free, the higher Al composition sam…
View article: Recent Advancements in N-polar GaN HEMT Technology
Recent Advancements in N-polar GaN HEMT Technology Open
N-polar GaN HEMT technology has emerged as a disruptive technology that outperforms Ga-polar GaN HEMTs in terms of high-frequency power amplification capability. In this paper, the authors present a comprehensive review of the evolution of…
View article: Integration of 150 nm gate length N-polar GaN MIS-HEMT devices with all-around diamond for device-level cooling
Integration of 150 nm gate length N-polar GaN MIS-HEMT devices with all-around diamond for device-level cooling Open
We report the successful integration of low-temperature polycrystalline all-around diamond as heat spreaders with 150 nm gate length N-polar GaN MISHEMT platform to improve power efficiencies for X-band applications. With an all-around int…
View article: High-Q, size-independent, and reconfigurable optical antennas via zero-index material dispersion engineering
High-Q, size-independent, and reconfigurable optical antennas via zero-index material dispersion engineering Open
Enhancing light-matter interactions at the nanoscale is foundational to nanophotonics, with epsilon near zero (ENZ) materials demonstrating significant potential.High-quality (Q) factor resonances maximizing these interactions are typicall…
View article: Optimizing TiN/Ru Schottky Contacts for N‐Polar GaN
Optimizing TiN/Ru Schottky Contacts for N‐Polar GaN Open
This study investigates the effect of titanium nitride (TiN) interlayers on the performance of ruthenium (Ru)‐based Schottky diodes on N‐polar GaN. The Ru Schottky diodes exhibited the highest mean Schottky barrier height of 0.69 0.03 eV; …
View article: Electrical and structural analysis of GaN/ZnO/Ga2O3 bonded interfaces; observation of spinel ZnGa2O4 after annealing
Electrical and structural analysis of GaN/ZnO/Ga2O3 bonded interfaces; observation of spinel ZnGa2O4 after annealing Open
The process of wafer bonding β-Ga2O3 and N-polar GaN with a ZnO “glue layer” was optimized to reduce resistance at the bonded interface. The GaN/ZnO and Ga2O3/ZnO interfaces were studied using TEM, with a focus on the effect of annealing o…
View article: Emerging GaN Technologies for Next-Generation Millimeter-Wave Applications
Emerging GaN Technologies for Next-Generation Millimeter-Wave Applications Open
International audience
View article: Investigative Forensic ToolKit Usage and Determinants of Adoption Behavior among Police Personnel
Investigative Forensic ToolKit Usage and Determinants of Adoption Behavior among Police Personnel Open
Technology has become integral to personal and professional spheres in the last two decades. There has been an unprecedented and rapid innovation in technology artifacts and their use for development and empowerment. Similarly, technology …
View article: N‐polar deep‐recess GaN MISHEMT with enhanced <i> f <sub>t</sub> ·L <sub>G</sub> </i> by gate dielectric thinning
N‐polar deep‐recess GaN MISHEMT with enhanced <i> f <sub>t</sub> ·L <sub>G</sub> </i> by gate dielectric thinning Open
The authors report a novel structure to improve the high‐frequency performance of nitrogen‐polar GaN deep‐recess high electron mobility transistors (HEMTs) wherein a timed plasma etch was used to tailor the profile of the gate dielectric. …
View article: Demonstration of HCl-Based Selective Wet Etching for N-Polar GaN with 42:1 Selectivity to Al0.24Ga0.76N
Demonstration of HCl-Based Selective Wet Etching for N-Polar GaN with 42:1 Selectivity to Al0.24Ga0.76N Open
A wet-etching technique based on a mixture of hydrochloric (HCl) and nitric (HNO3) acids is introduced, demonstrating exceptional 42:1 selectivity for etching N-polar GaN over Al0.24Ga0.76N. In the absence of an AlGaN etch stop layer, the …
View article: Trap Passivation for Reducing On-Resistance and Saturation Voltage in Wafer-Bonded InGaAs-Channel/GaN-Drain Vertical FETs
Trap Passivation for Reducing On-Resistance and Saturation Voltage in Wafer-Bonded InGaAs-Channel/GaN-Drain Vertical FETs Open
High frequency and high power are the driving forces behind semiconductor transistor technology. However, conventional devices have the tradeoff of either being high speed or high breakdown—but not both. Wafer-bonded current aperture verti…
View article: Electrical and Structural Analysis of <i>β</i>‐Ga<sub>2</sub>O<sub>3</sub>/GaN Wafer‐Bonded Heterojunctions with a ZnO Interlayer
Electrical and Structural Analysis of <i>β</i>‐Ga<sub>2</sub>O<sub>3</sub>/GaN Wafer‐Bonded Heterojunctions with a ZnO Interlayer Open
Wafer bonding of β ‐Ga 2 O 3 and N‐polar GaN single crystal substrates is demonstrated by adding ZnO as a “glue” interlayer. The wafers are fully bonded such that Newton rings are not observed. Temperature‐dependent current‐voltage ( I – V…
View article: N-Polar Indium Nitride Quantum Dashes and Quantum Wire-like Structures: MOCVD Growth and Characterization
N-Polar Indium Nitride Quantum Dashes and Quantum Wire-like Structures: MOCVD Growth and Characterization Open
The electrical properties of InN give it potential for applications in III-nitride electronic devices, and the use of lower-dimensional epitaxial structures could mitigate issues with the high lattice mismatch of InN to GaN (10%). N-polar …
View article: Gallium Nitride Versus Silicon Carbide: Beyond the Switching Power Supply [Industry View]
Gallium Nitride Versus Silicon Carbide: Beyond the Switching Power Supply [Industry View] Open
This article was jointly produced by IEEE Spectrum and PROCEEDINGS OF THE IEEE with similar versions published in both publications.
View article: Record RF Power Performance at 94 GHz From Millimeter-Wave N-Polar GaN-on-Sapphire Deep-Recess HEMTs
Record RF Power Performance at 94 GHz From Millimeter-Wave N-Polar GaN-on-Sapphire Deep-Recess HEMTs Open
In this article, N-polar GaN-on-sapphire deep-recess metal–insulator–semiconductor (MIS)-high-electron-mobility transistors (HEMTs) with a breakthrough performance at -band are presented. Compared with prior N-polar GaN MIS-HEMTs, a thin …
View article: Group-III nitride based high electron mobility transistor (HEMT) with barrier/spacer layer
Group-III nitride based high electron mobility transistor (HEMT) with barrier/spacer layer Open
A Group III nitride based high electron mobility transistors (HEMT) is disclosed that provides improved high frequency performance. One embodiment of the HEMT comprises a GaN buffer layer, with an Al.sub.y Ga.sub.1-y N (y=1 or y 1) layer o…
View article: Improved wall-plug efficiency of III-nitride tunnel junction micro-light-emitting diodes with AlGaN/GaN polarization charges
Improved wall-plug efficiency of III-nitride tunnel junction micro-light-emitting diodes with AlGaN/GaN polarization charges Open
The electrical performances of III-nitride blue micro-light-emitting diodes (µLEDs) with different tunnel junction (TJ) epitaxial architectures grown by metalorganic chemical vapor deposition are investigated. A new TJ structure that emplo…
View article: Fully Relaxed, Crack-Free AlGaN with upto 50% Al Composition Grown on Porous GaN Pseudo-Substrate
Fully Relaxed, Crack-Free AlGaN with upto 50% Al Composition Grown on Porous GaN Pseudo-Substrate Open
Fully relaxed, crack free, smooth AlxGa1−xN layers with up to 50% Al composition were demonstrated on pseudo-substrates composed of dense arrays of 10 × 10 µm2 compliant porous GaN-on-porous-GaN tiles. The AlGaN layers were grown in steps …
View article: Observation of self-assembled InGaN/GaN superlattice structure grown on N-polar GaN by plasma-assisted molecular beam epitaxy
Observation of self-assembled InGaN/GaN superlattice structure grown on N-polar GaN by plasma-assisted molecular beam epitaxy Open
In this paper, we report on the observation of self-assembled InGaN/(In)GaN superlattice (SL) structure in a nominal “InGaN” film grown on N-polar GaN substrate. 350 nm thick InGaN films were grown at different temperatures ranging from 60…
View article: Removal of chromium(VI) from aqueous solutions using mango leaf powder : Process optimization with Response Surface Methodology
Removal of chromium(VI) from aqueous solutions using mango leaf powder : Process optimization with Response Surface Methodology Open
Department of Chemical Engineering, National Institute of Technology Agartala, Agartala-799 046, Tripura, India Department of Civil Engineering, National Institute of Technology Agartala, Agartala-799 046, Tripura, India Department of Chem…
View article: Metal Organic Vapor Phase Epitaxy of Thick N-Polar InGaN Films
Metal Organic Vapor Phase Epitaxy of Thick N-Polar InGaN Films Open
Hillock-free thick InGaN layers were grown on N-polar GaN on sapphire by metal organic vapor phase epitaxy using a digital growth scheme and H2 as surfactant. Introducing Mg to act as an additional surfactant and optimizing the H2 pulse ti…
View article: CCDC 2023656: Experimental Crystal Structure Determination
CCDC 2023656: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: CCDC 2023657: Experimental Crystal Structure Determination
CCDC 2023657: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: CCDC 2023658: Experimental Crystal Structure Determination
CCDC 2023658: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: Comparative Assessment of Physico-Chemical Parameters of Lotic and Lentic Zone ofRiver Betwa in Jhansi (U.P.), India
Comparative Assessment of Physico-Chemical Parameters of Lotic and Lentic Zone ofRiver Betwa in Jhansi (U.P.), India Open
Water is the most precious natural gift given by God to human race. Its purity is also important for everyone. For the present study two sampling stations, Baratha village and Parichha dam head were selected for comparative assessment of p…
View article: CCDC 1965148: Experimental Crystal Structure Determination
CCDC 1965148: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: Compliant Micron-Sized Patterned InGaN Pseudo-Substrates Utilizing Porous GaN
Compliant Micron-Sized Patterned InGaN Pseudo-Substrates Utilizing Porous GaN Open
The compliant behavior of densely packed 10 × 10 µm2 square patterned InGaN layers on top of porous GaN is demonstrated. The elastic relaxation of the InGaN layers is enabled by the low stiffness of the porous GaN under layer. High resolut…
View article: AlGaN/GaN Superlattice‐Based p‐Type Field‐Effect Transistor with Tetramethylammonium Hydroxide Treatment
AlGaN/GaN Superlattice‐Based p‐Type Field‐Effect Transistor with Tetramethylammonium Hydroxide Treatment Open
To realize the full spectrum of advantages that the III‐nitride materials system offers, the demonstration of p‐channel III‐nitride‐based devices is valuable. The first p‐type field‐effect transistor (pFET) based on an AlGaN/GaN superlatti…
View article: Investigation of nitrogen polar p-type doped GaN/AlxGa(1-x)N superlattices for applications in wide-bandgap p-type field effect transistors
Investigation of nitrogen polar p-type doped GaN/AlxGa(1-x)N superlattices for applications in wide-bandgap p-type field effect transistors Open
In this study, the metal-organic chemical vapor deposition growth and electrical properties of N-polar modulation doped p-AlGaN/GaN superlattices (SLs) were investigated. Hole sheet charge density and mobility were studied as a function of…