Mohammad Sadegh Nazari

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Direct measurements are reported of self-heating in an AlGaN/GaN transistor using ultraviolet and visible micro-Raman. Device stack is comprised of silicon substrate, AlN nucleation, AlGaN transition, GaN buffer, and AlGaN barrier layers. Phonon shifts are used to estimate temperature rise. Ultraviolet measurements probe the current- carrying GaN near the(More)
Visible and ultraviolet (UV) micro-Raman spectroscopies are used to study the stress in GaN integrated with diamond grown by chemical vapor deposition. Mapping of stress is accomplished across a 75-mm GaN-on-diamond wafer. UV measurements from both sides of the wafer reveal an unexpected gradient between the tensile stress from the free GaN surface (~0.86(More)
OBJECTIVE Accurate delivery of torque to implant screws is critical to generate ideal preload in the screw joint and to offer protection against screw loosening. Mechanical torque-limiting devices (MTLDs) are available for this reason. In this study, the accuracy of one type of friction-style and two types of spring-style MTLDs at baseline, following(More)
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