Compact, Pull-in-Free Electrostatic MEMS Actuated Tunable Ring Resonator for Optical Multiplexing
Abstract not provided.
Publications
Characterization and Modeling of DC & RF Breakdown in Microscale Gaps near Vacuum
Abstract not provided.
Germanium Telluride Chalcogenide Switches for RF Applications
This project developed prototype germanium telluride switches, which can be used in RF applications to improve SWAP (size, weight, and power) and signal quality in RF systems. These switches can allow for highly reconfigurable systems, including antennas, communications, optical systems, phased arrays, and synthetic aperture radar, which all have high impact on current National Security goals for improved communication systems and communication technology supremacy. The final result of the project was the demonstration of germanium telluride RF switches, which could act as critical elements necessary for a single chip RF communication system that will demonstrate low SWAP and high reconfigurability
AlGaN Transistors for Digital Logic Applications in High-Temperature Environments
Abstract not provided.
Compact, Pull-in-Free Electrostatic MEMS Actuated Tunable Ring Resonator for Optical Multiplexing
Abstract not provided.
AlGaN High Electron Mobility Transistor for Power Switches and High Temperature Logic
Abstract not provided.
Sandia Microsystem and Integration
Abstract not provided.
On-Wafer Microfabricated Test Structures for Characterizing RF Breakdown in Narrow Gaps
Proceedings of the 2021 IEEE Texas Symposium on Wireless and Microwave Circuits and Systems: Making Waves in Texas, WMCS 2021
Plasmas formed in microscale gaps at DC and plasmas formed at radiofrequency (RF) both deviate in behavior compared to the classical Paschen curve, requiring lower voltage to achieve breakdown due to unique processes and dynamics, such as field emission and controlled rates of electron/ion interactions. Both regimes have been investigated independently, using high precision electrode positioning systems for microscale gaps or large, bulky emitters for RF. However, no comprehensive study of the synergistic phenomenon between the two exists. The behavior in such a combined system has the potential to reach sub-10 V breakdown, which combined with the unique electrical properties of microscale plasmas could enable a new class of RF switches, limiters and tuners.This work describes the design and fabrication of novel on-wafer microplasma devices with gaps as small as 100 nm to be operated at GHz frequencies. We used a dual-sacrificial layer process to create devices with microplasma gaps integrated into RF compatible 50 Ω coplanar waveguide transmission lines, which will allow this coupled behaviour to be studied for the first time. These devices are modelled using conventional RF simulations as well as the Sandia code, EMPIRE, which is capable of modelling the breakdown and formation of plasma in microscale gaps driven by high frequencies. Synchronous evaluation of the modelled electrical and breakdown behaviour is used to define device structures, predict behaviour and corroborate results. We further report preliminary independent testing of the microscale gap and RF behaviour. DC testing shows modified-Paschen curve behaviour for plasma gaps at and below four microns, demonstrating decreased breakdown voltage with reduced gap size. Additionally, preliminary S-parameter measurements of as-prepared and connectorized devices have elucidated RF device behaviour. Together, these results provide baseline data that enables future experiments as well as discussion of projected performance and applications for these unique devices.
On-Wafer Microfabricated Test Structures for Characterizing RF Breakdown in Narrow Gaps
Abstract not provided.
HIPR-RF Hetergeneous Integration for Parasitic Loss in RF Microsystems
Abstract not provided.
On-Wafer Microfabricated Test Structures for Characterizing RF Breakdown in Narrow Gaps
Abstract not provided.
Extending the Frequency of Piezoelectric Resonators to Microwave Frequencies and Beyond
Abstract not provided.
GAUSSIAN FOCUSED CAVITY FILTER DESIGN
Abstract not provided.
AlN-Alloyed-Based Wideband Multiplexers for Situational Spectral Awareness
Abstract not provided.
High Density Microbump Development for Multi-Project Wafer (MPW) Die
Abstract not provided.
Heterogeneous Integration of Silicon Electronics and Compound Semiconductor Optoelectronics for Miniature RF Photonic Transceivers
Abstract not provided.
Heterogeneous Integration of 3D Photonic Integrated Circuits
Abstract not provided.
AlGaN HEMT Logic for Extreme Temperature Operation
Abstract not provided.
Device-level thermal management of gallium oxide field-effect transistors
IEEE Transactions on Components, Packaging and Manufacturing Technology
The ultrawide bandgap (UWBG) (4.8 eV) and melt-grown substrate availability of β-Ga2O3 give promise to the development of next-generation power electronic devices with dramatically improved size, weight, power, and efficiency over current state-of-the-art WBG devices based on 4H-SiC and GaN. Also, with recent advancements made in gigahertz frequency radio frequency (RF) applications, the potential for monolithic or heterogenous integration of RF and power switches has attracted researchers' attention. However, it is expected that Ga2O3 devices will suffer from self-heating due to the poor thermal conductivity of the material. Thermoreflectance thermal imaging and infrared thermography were used to understand the thermal characteristics of a MOSFET fabricated via homoepitaxy. A 3-D coupled electrothermal model was constructed based on the electrical and thermal characterization results. The device model shows that a homoepitaxial device suffers from an unacceptable junction temperature rise of 1500 °C under a targeted power density of 10 W/mm, indicating the importance of employing device-level thermal managements to individual Ga2O3 transistors. The effectiveness of various active and passive cooling solutions was tested to achieve a goal of reducing the device operating temperature below 200 °C at a power density of 10 W/mm. Results show that flip-chip heterointegration is a viable option to enhance both the steady-state and transient thermal characteristics of Ga2O3 devices without sacrificing the intrinsic advantage of high-quality native substrates. Also, it is not an active thermal management solution that entails peripherals requiring additional size and cost implications.
Saturation Velocity Measurement of Al0.7Ga0.3N-Channel High Electron Mobility Transistors
Journal of Electronic Materials
Gate length dependent (80 nm–5000 mm) radio frequency measurements to extract saturation velocity are reported for Al0.85Ga0.15N/Al0.7Ga0.3N high electron mobility transistors fabricated into radio frequency devices using electron beam lithography. Direct current characterization revealed the threshold voltage shifting positively with increasing gate length, with devices changing from depletion mode to enhancement mode when the gate length was greater than or equal to 450 nm. Transconductance varied from 10 mS/mm to 25 mS/mm, with the 450 nm device having the highest values. Maximum drain current density was 268 mA/mm at 10 V gate bias. Scattering-parameter characterization revealed a maximum unity gain bandwidth (fT) of 28 GHz, achieved by the 80 nm gate length device. A saturation velocity value of 3.8 × 106 cm/s, or 35% of the maximum saturation velocity reported for GaN, was extracted from the fT measurements.
Cryogenic Performance of Microfabricated Surface Ion Traps
Abstract not provided.
Ultra-Wide-Bandgap Aluminum Gallium Nitride Devices for Radio-Frequency Applications (invited)
Abstract not provided.
Ultra-Wide-Bandgap Aluminum Gallium Nitride Devices for Radio-Frequency Applications
Abstract not provided.
RF Performance of Al0.85Ga0.15N/Al0.70Ga0.30N high electron mobility transistors with 80-nm Gates
IEEE Electron Device Letters
Al-rich AlGaN-channel high electron mobility transistors with 80-nm long gates and 85% (70%) Al in the barrier (channel) were evaluated for RF performance. The dc characteristics include a maximum current of 160 mA/mm with a transconductance of 24 mS/mm, limited by source and drain contacts, and an on/off current ratio of 109. fT of 28.4 GHz and fMAX of 18.5 GHz were determined from small-signal S-parameter measurements. Output power density of 0.38 W/mm was realized at 3 GHz in a power sweep using on-wafer load pull techniques.
A Cryogenic Environment for Microfabricated Surface Electrode Ion Traps
Abstract not provided.
Results 1–25 of 136