Characterization of Devices and Materials for Gallium Nitride and Diamond Thermal Management Applications
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As trends progress toward higher power applications in GaN-based electronic and photonic devices, the issue of self-heating becomes a prominent concern. This is especially the case for high-brightness light-emitting diodes (LEDs) and high electron mobility transistors (HEMTs), where the bulk of power dissipation occurs within a small (sub-micron) region resulting in highly localized temperature rises during operation. Monitoring these thermal effects becomes critical as they significantly affect performance, reliability, and overall device lifetime. In response to these issues, diamond grown by chemical vapor deposition (CVD) has emerged as a promising material in III-nitride thermal management as a heat-spreading substrate due to its exceptional thermal conductivity. This work is aimed toward the characterization of self-heating and thermal management technologies in GaN electronic and photonic devices and their materials. The two main components of this dissertation include assessing self-heating in these devices through direct measurement of temperature rises in high-power LEDs and GaN HEMTs and qualifying thermal management approaches through the characterization of thermal conductivity and material quality in CVD diamond and its incorporation into GaN device layers. The purpose of this work is to further the understanding of thermal effects in III-nitride materials as well as provide useful contributions to the development of future thermal management technologies in GaN device applications.