A5056320673- GaN-based semiconductor devices and materials
- Ga2O3 and related materials
- ZnO doping and properties
- Silicon Carbide Semiconductor Technologies
- Acoustic Wave Resonator Technologies
- Gas Sensing Nanomaterials and Sensors
- Semiconductor materials and devices
- Magnetic Field Sensors Techniques
- Advanced MEMS and NEMS Technologies
- Sensor Technology and Measurement Systems
- Mechanical and Optical Resonators
- Non-Destructive Testing Techniques
- Nanowire Synthesis and Applications
- Thermal properties of materials
- Diamond and Carbon-based Materials Research
- Advanced Thermoelectric Materials and Devices
- Ferroelectric and Piezoelectric Materials
- Graphene research and applications
- Advanced Sensor Technologies Research
- Radiation Effects in Electronics
- Thin-Film Transistor Technologies
- Plasma Diagnostics and Applications
- Semiconductor Quantum Structures and Devices
- Metal and Thin Film Mechanics
- Photocathodes and Microchannel Plates
Stanford University
2016-2025
Vaughn College of Aeronautics and Technology
2016-2025
XLAB (Slovenia)
2023
Palo Alto University
2012-2022
Carnegie Mellon University
2021
Materials Science & Engineering
2021
Robotics Research (United States)
2021
Ames Research Center
2021
American Institute of Aeronautics and Astronautics
2013-2020
Université Jean Monnet
2019
Advances in siliconcarbide microfabrication and growth process optimization for nanostructures are ushering new opportunities microdevices capable of operation a variety demanding applications, involving high temperature, radiation, or corrosive environment. This review focuses on the materials science processing technologies siliconcarbidethin films low dimensional structures, details recent progress manufacturing technology, including deposition, metallization, fabrication semiconductor...
An AlN/3C–SiC composite layer enables the third-order quasi-symmetric (QS3) Lamb wave mode with a high quality factor (Q) characteristic and an ultra-high phase velocity up to 32395 ms−1. A resonator utilizing QS3 exhibits low motional impedance of 91 Ω Q 5510 at series resonance frequency (fs) 2.92 GHz, resulting in highest fs·Q product 1.61 × 1013 Hz among suspended piezoelectric thin film resonators reported date.
We demonstrate solar-blind photodetectors (PDs) by employing AlN thin films on Si(100) substrates with excellent temperature tolerance and radiation hardness. Even at a bias higher than 200 V the PDs Si show dark current as low ~ 1 nA. The working is up to 300°C 10(13) cm(-2) of 2-MeV proton fluences for metal-semiconductor-metal (MSM) PDs. Moreover, photoresponse time fast 110 ms (the rise time) 80 fall 5 bias. results that MSM hold high potential in next-generation deep ultraviolet use...
A high-performance temperature sensor based on 4H-SiC pn diode is demonstrated. The capable of stable operation in a range from 20 °C to 600 °C. forward voltage the has linear dependence variation at constant current, and recombination current dominates flowing measured range. At density 0.44 mA/cm2, device achieves sensitivity 3.5 mV/ This type can be integrated with SiC power management control circuitry create sensing module that working extremely high temperatures.
Studies of laser-heated materials on femtosecond timescales have shown that the interatomic potential can be perturbed at sufficiently high laser intensities. For gold, it has been postulated to undergo a strong stiffening leading an increase phonon energies, known as hardening. Despite efforts investigate this behavior, only measurements low absorbed energy density performed, for which interpretation experimental data remains ambiguous. By using in situ single-shot x-ray diffraction hard...
A Lamb wave resonator utilizing an aluminum nitride (AlN) plate with biconvex edges to enhance the quality factor (Q) is demonstrated. The simulation results based on finite element analysis verify that use of edges, instead conventional flat can efficiently confine mechanical energy in AlN resonator. Specifically, measured frequency response a 491.8-MHz yields Q 3280 which represents 2.6× enhancement over 517.9-MHz same but suspended edges.
This work demonstrates the high-temperature operation of metal-semiconductor-metal (MSM) photodetectors (PDs) up to 450 °C using lightly Al-doped epitaxial 4H-SiC thin films. The responsivity PDs under 325-nm illumination is 0.0305 A/W at 20-V bias room temperature. photocurrentto-dark-current ratio SiC MSM as high 1.3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> 25 and 0.62 °C. rise/fall time increased slightly from 594 μs/684...
Photodetectors based on the AlGaN/GaN heterostructure suffer from persistent photoconductivity (PPC) in which recovery optical stimulus can take days. This behavior is unsuitable for many applications where reliable and consistent response required. letter presents a method suppressing PPC photodetectors by employing device suspension situ heating. The highly conductive two-dimensional electron gas (2DEG) at interface of AlGaN GaN serves as both sensor heater (via Joule heating)....
An ultraviolet (UV) photodetector employing the two-dimensional electron gas (2DEG) formed at AlGaN/GaN interface as an interdigitated transducer (IDT) is characterized under optical stimulus. The 2DEG-IDT exhibits a record high normalized photocurrent-to-dark current ratio of 6 × 1014. We also observe responsivity (7800 A/W) and ultraviolet–visible rejection (106), among highest reported values for any GaN architecture. argue that valence band offset in heterostructure essential achieving...
This letter reports an enhancement-mode (E-mode) GaN transistor technology which has been demonstrated to operate in a simulated Venus environment (460 °C, ~ 92 atm., containing CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /N /SO etc.) for 10 days. The robustness of the W/p-GaN-gate AlGaN/GaN high electron mobility (HEMT) was evaluated by two complementary approaches, (1) <italic...
Highly c-axis oriented heteroepitaxial aluminum nitride (AlN) films were grown on epitaxial cubic silicon carbide (3C–SiC) layers Si (100) substrates using alternating current reactive magnetron sputtering at temperatures between approximately 300–450 °C. The AlN characterized by x-ray diffraction, scanning electron microscope, and transmission microscopy. A two-port surface acoustic wave device was fabricated the AlN/3C–SiC/Si composite structure, an expected Rayleigh mode exhibited a high...
Surface acoustic wave (SAW) propagation characteristics in a multilayer structure including piezoelectric aluminum nitride (AlN) thin film and an epitaxial cubic silicon carbide (3C–SiC) layer on (Si) substrate are investigated by theoretical calculation this work. Alternating current (ac) reactive magnetron sputtering was used to deposit highly c-axis-oriented AlN films, showing the full width at half maximum (FWHM) of rocking curve 1.36° 3C–SiC layers Si substrates. In addition,...
Formation of allowed and stopped frequency bands elastic wave propagation in the periodic media, also known as phononic crystal (PnC), recently has attracted great attention enabling high quality factor (Q) electroacoustic devices. To eliminate anchor loss, acoustic band gap structures are employed support tethers aluminum nitride (AlN) Lamb resonators. The PnC strip which made cross-shape beams based on 4-μm-thick AlN slab well designed to reduce loss then significantly increase Q's devices...
Micromachining silicon carbide (SiC) is challenging due to its durable nature. However, plasma and laser etch processes have been utilized realize deep high aspect ratio (HAR) features in SiC substrates films. HAR topologies can improve SiC-based MEMS transducers (reduced electrostatic gaps) enable embedded substrate cooling features. Our process used inductive coupled (ICP) etching with sulfur hexafluoride (SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Three-dimensional heterostructured AlGaN/GaN ultraviolet (UV) photodetectors were microfabricated using V-grooved silicon(111) surfaces and metal organic chemical vapor deposition. This novel sensor platform enabled an increase in sensitivity operation at high temperatures (up to 200°C). More specifically, texturizing the highly conductive 2-D electron gas V-groove surfaces, resulted higher photodetector (57.4% room temperature 139% 200°C) compared with conventional designs on planar...
3D coil structures through 2D processing, combined with ferrofluid core, achieve unprecedented high magnetic flux density.
The magnetic sensitivity of Hall-effect sensors made InAlN/GaN and AlGaN/GaN heterostructures was measured between room temperature 576 °C. Both devices showed decreasing voltage-scaled at high temperatures, declining from 53 mV/V/T to 8.3 for the sample 89 8.5 sample, corresponding electron mobility due scattering effects elevated temperatures. Alternatively, current-scaled sensitivities remained stable over range, only varying by 13.1% mean 26.3 V/A/T 10.5% 60.2 samples, respectively. This...
Abstract We present a method to determine the bulk temperature of single crystal diamond sample at an X-Ray free electron laser using inelastic X-ray scattering. The experiment was performed high energy density instrument European XFEL GmbH, Germany. technique, based on scattering and principle detailed balance, demonstrated give accurate measurements, within $$8\%$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>8</mml:mn> <mml:mo>%</mml:mo> </mml:mrow>...
We report for the first time on an aluminum nitride/gallium nitride (AlN/GaN) heterostructure as a microscale Hall effect sensor current sensing applications in extreme environments. The AlN/GaN devices demonstrated high signal linearity function of magnetic field across temperature range from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 193...