  We investigate the morphology of quasi-free-standing monolayer graphene
(QFMLG) formed at several temperatures by hydrogen intercalation and discuss
its relationship with transport properties. Features corresponding to
incomplete hydrogen intercalation at the graphene-substrate interface are
observed by scanning tunneling microscopy on QFMLG formed at 600 and
800{\deg}C. They contribute to carrier scattering as charged impurities. Voids
in the SiC substrate and wrinkling of graphene appear at 1000{\deg}C, and they
decrease the carrier mobility significantly.
