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.
@article{arxiv.1810.10623,
title = {Microscopy of hydrogen and hydrogen-vacancy defect structures on graphene devices},
author = {Dillon Wong and Yang Wang and Wuwei Jin and Hsin-Zon Tsai and Aaron Bostwick and Eli Rotenberg and Roland K. Kawakami and Alex Zettl and Arash A. Mostofi and Johannes Lischner and Michael F. Crommie},
journal= {arXiv preprint arXiv:1810.10623},
year = {2018}
}