Kris, it has been mostly GaN on Sapphire so far because the epitaxy buffer layer AlN and the active layer InGaN have so far been processed mostly on Sapphire. That is not the only substrate of choice, there is bulk GaN, SiC (early Cree versions), Si and composites.
If yield issues are proven, it makes sense to move away from Sapphire. Ideally, the LED industry has to work toward vertical designs with backside contact which can result in smaller chips. It is not clear if moving to Si substrate achieves that.
It is ironic, Toshiba on one end announced cut in its NAND Flash production by 30%.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Are the design challenges the same as with embedded systems, but with a little developer- and IT-skills added in? What do engineers need to know? Rick Merritt talks with two experts about the tools and best options for designing IoT devices in 2016. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.