- Wong, Dillon;
- Wang, Yang;
- Jin, Wuwei;
- Tsai, Hsin-Zon;
- Bostwick, Aaron;
- Rotenberg, Eli;
- Kawakami, Roland K;
- Zettl, Alex;
- Mostofi, Arash A;
- Lischner, Johannes;
- Crommie, Michael F
We have used scanning tunneling microscopy (STM) to investigate two types of hydrogen defect structures on monolayer graphene supported by hexagonal boron nitride (h-BN) in a gated field-effect transistor configuration. The first H-defect type is created by bombarding graphene with 1-keV ionized hydrogen and is identified as two hydrogen atoms bonded to a graphene vacancy via comparison of experimental data to first-principles calculations. The second type of H defect is identified as dimerized hydrogen and is created by depositing atomic hydrogen having only thermal energy onto a graphene surface. Scanning tunneling spectroscopy (STS) measurements reveal that hydrogen dimers formed in this way open a new elastic channel in the tunneling conductance between an STM tip and graphene.