| AVS 65th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Wednesday Sessions |
| Session PS+AS+EL+EM+SE-WeM |
| Session: | Current and Future Stars of the AVS Symposium I |
| Presenter: | Rachael Myers-Ward, U.S. Naval Research Laboratory |
| Authors: | R.L. Myers-Ward, U.S. Naval Research Laboratory J. Kim, Massachusetts Institute of Technology M.T. DeJarld, US Naval Research Laboratory K. Qiao, Massachusetts Institute of Technology Y. Kim, Massachusetts Institute of Technology S.P. Pavunny, U.S. Naval Research Laboratory D.K. Gaskill, U.S. Naval Research Laboratory |
| Correspondent: | Click to Email |
Ideally, electronic heterostructures from dissimilar materials leads to enhanced functionality. Yet, experimentally forming these heterostructures is challenging due to lattice or thermal coefficient of expansion mismatch leading to defect formation or thermally driven atomic diffusion resulting in cross-doping and gradual junction transitions. These challenges may be overcome with the discovery of remote epitaxy and 2D layer transfer [1]. Here, SiC epitaxy is performed on epitaxial graphene as the electrostatic fields from the substrate penetrate the graphene and guide adatom registry. The film is easily peeled away since the graphene is not bonded to either the substrate or epilayer; the epilayer is then van der Waals bonded to a different material enabling new functionality. We will present experimental results on the remote epitaxy of SiC, illustrating potential quantum science applications.
There are three necessary steps to create remote epitaxy. The first is to grow epitaxial graphene on SiC, followed by transferring the graphene to a desired substrate (if different from SiC), and finally the growth of the remote epitaxial layer. If the remote epitaxy is to be SiC, which is the focus of this paper, the second step is not needed. Epitaxial graphene (EG) was first synthesized on 4H- and 6H-SiC in a horizontal hot-wall CVD reactor between 1540 and 1580 °C in 10 slm of Ar and 100 mbar [2]. The growth temperature was dependent upon the offcut of the substrate, where substrates with higher offcuts require a lower growth temperature to ensure 1 ML of EG, which is desired to assist in SiC adatom registry during growth. SiC remote epitaxy was then performed on the EG using silane (2% in H2) and propane precursors, where the SiC polytype replicated the underlying substrate. In an effort to transfer the remote SiC epi/EG to another substrate such as SiO2/Si, a metallization step was performed. Thin Ti and/or Ni layers were initially deposited followed by a thicker high stress metal to create strain and aide in removing the remote SiC epi/EG from the SiC substrate [1]. Once transferred, the metal was removed via a metal etch.
In this work, we will discuss the important parameters needed for successful remote SiC epitaxy, such as metallization, graphene thickness and remote epitaxy growth temperature. The epitaxial morphology characterized by SEM and Nomarski microscopy and graphene coverage and transfer evaluated by Raman spectroscopy will be presented.
[1] Kim, et al., Nature 544, 340 (2017).
[2] L.O. Nyakiti, et al., MRS Bulletin 37, 1150 (2017).