Fig. 8
Effect of hydrogen on 2D materials. a Changes in Raman spectra of graphene caused by hydrogen. Left is Graphene on SiO2 and right is free-standing graphene. Red, blue, and green curves correspond to pristine, hydrogenated, and annealed samples, respectively. Figure reproduced from ref. [212], AAAS. b Raman spectra taken from an as-grown GaN film on graphene/SiC, released GaN films on the tape, remaining graphene after GaN release and GaN film transferred on SiO2 substrate. c HRTEM observed at the interface between GaN and SiC showing graphene remains after growth. Top image is GaN grown on a fresh graphene/SiC and bottom image is GaN grown on a reused graphene/SiC substrate. Figure reproduced from ref. [8], Springer Nature Ltd. d STEM image of GaN grown on graphene/c-sapphire confirming graphene remains. e Annealing test of wet-transferred graphene on c-sapphire at 1050 ºC ambient in H2. Figure reproduced from ref. [199], AAAS. f high-magnification CCD image of the interface between AlN and c-sapphire confirming the presence of h-BN layer. Figure reproduced from ref. [213], Elsevier. g 5 nm-thick h-BN layer as grown on AlN. h annealed h-BN on AlN at 1400 ºC ambient in H2. i FTIR spectra for confirming the presence of h-BN after annealing. Figure reproduced from ref. [203], RSC Publishing