Thermal Transport in III-V Semiconductors and Devices
Christensen, Adam Paul
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It is the objective of this work to focus on heat dissipation in gallium nitride based solid-state logic devices as well as optoelectronic devices, a major technical challenge. With a direct band gap that is tunable through alloying between 0.7-3.8 eV, this material provides an enabling technology for power generation, telecommunications, power electronics, and advanced lighting sources. Previously, advances in these areas were limited by the availability of high quality material and growth methods, resulting in high dislocation densities and impurities. Within the last 40 years improvements in epitaxial growth methods such as lateral epitaxial overgrowth (LEO), hydride vapor phase epitaxy (HVPE), molecular beam epitaxy (MBE), and metal organic chemical vapor deposition (MOCVD), has enabled electron mobilities greater than 1600 cm2V/s, with dislocation densities less than 109/cm2. Increases in device performance with improved materials have now been associated with an increase in power dissipation (>1kW/cm2) that is limiting further development. In the following work thermophysical material of III-V semiconducting thin films and associated substrates are presented. Numerical modeling coupled with optical (micro-IR imaging and micro-Raman Spectroscopy) methods was utilized in order to study the heat carrier motion and the temperature distribution in an operating device. Results from temperature mapping experiments led to an analysis for design of next generation advancements in electronics packaging.