Improvements in SiC Remote Epitaxy for Stackable Electronics

Remote epitaxy (RE) is a growth process performed on a graphene-covered substrate where the adatom registry is guided by the electrostatic fields penetrating through the graphene from the underlying substrate rather than interactions with the graphene lattice. The RE-grown material is easily exfoliated from the substrate due to weak van der Waals bonding of the graphene at the interface, enabling transfer to desired substrates and thus enabling heterostructures that typically cannot be created with current methods. This technique has the possibility of impacting several research areas including SiC and GaN SMART power, heterogeneous integration of opto- and electronic devices, improving HEMT performance by transferring to higher thermal conductivity substrates, flexible electronics and quantum sciences.<br/> In this work, we focus on the RE of SiC grown on epitaxial graphene on SiC (0001) using a hot-wall chemical vapor deposition reactor. To maintain the graphene during SiC remote epitaxy, a study was conducted comparing the carrier gas during SiC remote epitaxial growth in an Ar/H₂ to an all-Ar growth process. The graphene thickness was varied between 1-5 monolayers by using SiC substrates with different offcuts to see the effect of different layer counts on SiC RE. Single crystalline material was achieved for both the on- and off-axis substrates when a low C/Si ratio was used in both an Ar/H₂ and all Ar carrier gas flow. Films were characterized using Nomarski microscopy, atomic force microscopy, x-ray diffraction, scanning electron microscopy, transmission electron microscopy and electron backscatter diffraction. While SiC was grown in these experiments, continuous graphene did not remain. Using a high C/Si ratio during the initiation of growth increased the amount of graphitic carbon present at the interface after SiC RE. We will present these results along with studies of using a silane precursor 2% diluted in Ar instead of H₂ to reduce etching effects of graphene during the initiation of SiC RE.<br/> <br/>Research at NRL was supported by the Office of Naval Research.<br/> DISTRIBUTION STATEMENT A: Approved for public release, distribution is unlimited.