One-step graphene coating of heteroepitaxial GaN films.
Today, state-of-the-art III-Ns technology has been focused on the growth of c-plane nitrides by metal-organic chemical vapor deposition (MOCVD) using a conventional two-step growth process. Here we show that the use of graphene as a coating layer allows the one-step growth of heteroepitaxial GaN films on sapphire in a MOCVD reactor, simplifying the GaN growth process. It is found that the graphene coating improves the wetting between GaN and sapphire, and, with as little as ~0.6 nm of graphene coating, the overgrown GaN layer on sapphire becomes continuous and flat. With increasing thickness of the graphene coating, the structural and optical properties of one-step grown GaN films gradually transition towards those of GaN films grown by a conventional two-step growth method. The InGaN/GaN multiple quantum well structure grown on a GaN/graphene/sapphire heterosystem shows a high internal quantum efficiency, allowing the use of one-step grown GaN films as 'pseudo-substrates' in optoelectronic devices. The introduction of graphene as a coating layer provides an atomic playground for metal adatoms and simplifies the III-Ns growth process, making it potentially very useful as a means to grow other heteroepitaxial films on arbitrary substrates with lattice and thermal mismatch.
School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Korea.
Jae-Kyung
JK
Choi
Jae-Hoon
JH
Huh
Sung-Dae
SD
Kim
Daeyoung
D
Moon
Duhee
D
Yoon
Kisu
K
Joo
Jinsung
J
Kwak
Jae Hwan
JH
Chu
Sung Youb
SY
Kim
Kibog
K
Park
Young-Woon
YW
Kim
Euijoon
E
Yoon
Hyeonsik
H
Cheong
Soon-Yong
SY
Kwon