Innovative Manufacturing Process Improvements - GaN On SOD

The purpose of the proposed research will be to develop GaN molecular beam epitaxy on SOD (silicon/diamond/silicon) substrates up to 4 inches in diameter. This unique substrate/epilayer combination will provide electronic materials suitable for high-power and opto-electronic devices without the commonly observed limitations due to the production of excess heat during device operation. The resulting devices will have built-in thermal heat spreading capability that should result in better performance and higher reliability. It will also have the capability of being extended to wafer sizes of 200mm or larger. This project will combine sp3's expertise in growing diamond on silicon with existing SOI technology that can apply a thin layer of single crystal silicon on top of the diamond to form an SOD structure. UC Berkeley's existing expertise in buffer layer development for GaN growth by MBE on silicon can then be used to create a device layer on top of the silicon. The resulting device has an integral heat spreader incorporated into the substrate that can improve both device performance and reliability. A precise, flat, stress free silicon/diamond intermediate substrate is an essential part of this research project and will be the primary focus. Device modeling prior to manufacturing the SOD substrate will be used to pre-optimize the diamond and silicon layer thickness' and fabricated device measurements will be used to refine the model and evaluate the improvements in performance and junction temperatures as a result of the diamond layer.