posted on 2021-04-26, 16:08authored byKuan Qiao, Yunpeng Liu, Chansoo Kim, Richard J. Molnar, Tom Osadchy, Wenhao Li, Xuechun Sun, Huashan Li, Rachael L. Myers-Ward, Doyoon Lee, Shruti Subramanian, Hyunseok Kim, Kuangye Lu, Joshua A. Robinson, Wei Kong, Jeehwan Kim
Free-standing
crystalline membranes are highly desirable owing
to recent developments in heterogeneous integration of dissimilar
materials. Van der Waals (vdW) epitaxy enables the release of crystalline
membranes from their substrates. However, suppressed nucleation density
due to low surface energy has been a challenge for crystallization;
reactive materials synthesis environments can induce detrimental damage
to vdW surfaces, often leading to failures in membrane release. This
work demonstrates a novel platform based on graphitized SiC for fabricating
high-quality free-standing membranes. After mechanically removing
epitaxial graphene on a graphitized SiC wafer, the quasi-two-dimensional
graphene buffer layer (GBL) surface remains intact for epitaxial growth.
The reduced vdW gap between the epilayer and substrate enhances epitaxial
interaction, promoting remote epitaxy. Significantly improved nucleation
and convergent quality of GaN are achieved on the GBL, resulting in
the best quality GaN ever grown on two-dimensional materials. The
GBL surface exhibits excellent resistance to harsh growth environments,
enabling substrate reuse by repeated growth and exfoliation.