Epitaxial growth optimization of AlGaN/GaN high electron mobility transistor structures on 3C-SiC/Si

Abstract

The excellent characteristics of high electron mobility transistors based on AlGaN/GaN heterostructures rely on the properties of the substrate used for their epitaxial growth. In this work, we evaluate 3C-SiC as an alternative to the commonly used 4H-SiC. Up to 2 μm thick 3C-SiC layers on Si templates have been used as substrates to develop an epitaxial growth process for high-quality AlGaN/GaN heterostructures. We demonstrate the deposition of up to 5 μm crack-free heterostructures on 2 μm thick 3C-SiC on Si by using a metalorganic chemical vapor deposition process. Several characteristics of these structures, such as crystal quality, morphology, and electrical properties, are close to what can be achieved when using 4H-SiC substrates. The results of this work motivate further development in order to obtain thicker and semi-insulating 3C-SiC layers to be used instead of the expensive and size-limited 4H-SiC substrates.