Direct high-temperature growth of GaN on Si using trimethylaluminum preflow enabling vertically-conducting heterostructures

In this work, we demonstrate that GaN can be directly grown at high temperature on Si(111) substrates by metalorganic chemical vapor deposition without using any intentional AlN buffer, by simply employing a trimethylaluminum (TMAl) preflow. We found that n-GaN layers directly grown on n-Si with a TMAl preflow not only present a better crystalline quality compared to the use of thin AlN buffers, but also exhibit orders-of-magnitude improvement in vertical current conduction between GaN and Si, thanks to the absence of highly resistive AlN layers. Our proposed technique opens a new pathway for the effective realization of fully-vertical GaN-on-Si devices.