Pulsed-Mode Metalorganic Vapor-Phase Epitaxy of GaN on Graphene-Coated c-Sapphire for Freestanding GaN Thin Films

Remote Epitaxy: Fundamentals, Challenges, and Opportunities

“…The only obstacle to this approach is that not all substrates are suitable for graphene growth due to the high growth temperature of graphene. Currently, therefore, the reports on remote epitaxy based on directly grown graphene are limited to a few types of substrates, including SiC, ,, Ge, SrTiO 3 , and sapphire …”

“…These reports on failures of remote epitaxy by damage to 2D materials provide valuable insights into mitigating the issue. Based on these findings, successful remote epitaxy of III-V and III-N has been achieved by introducing several tactics, such as (a) utilizing nitrogen as a carrier gas, , (b) introducing low-temperature nucleation stages, ,, and (c) employing more robust graphene templates, such as graphitized SiC. , Employing MBE instead of MOCVD could also be an effective approach for the remote epitaxy of these materials, , because the growth environment is less harsh in MBE as it employs a lower temperature, lower pressure, and elemental sources.…”

“…Second, screened electrostatic interaction from the substrate promotes Volmer–Weber growth mode, making it often difficult to form fully merged and planarized thin films . Therefore, the growth conditions need to be modified from standard conditions for enhanced nucleation density. ,, Intentional formation of dangling bonds on 2D materials by plasma treatment can also be employed in remote epitaxy to enhance the nucleation density, , although the conditions used for plasma treatment have to be carefully controlled to prevent the occurrence of other growth modes, such as quasi-vdW (qvdW) epitaxy and pinhole-based selective epitaxy.…”