Thermally driven hydrogen interaction with single-layer graphene on SiO2/Si substrates quantified by isotopic labeling

Abstract

In the present work, we investigated the interaction of hydrogen with single-layer graphene. Fully hydrogenated monolayer graphene was predicted to be a semiconductor with a bandgap of 3.5 eV in contrast to the metallic behavior of its pristine counterpart. Integration of these materials is a promising approach to develop new electronic devices. Amidst numerous theoretical works evidencing the efficient formation of fully hydrogenated graphene, few experimental studies have tackled this issue. A possible explanation for that is the difficulty to directly quantify hydrogen by usual characterization techniques. Using an isotopically enriched gas in deuterium in conjunction with nuclear reaction analysis, we were able to quantify deuterium deliberately incorporated in graphene as a result of thermal annealing. The highest D areal density obtained following annealing at 800 °C was 3.5 × 1014 D/cm2. This amount corresponds to ∼10% of the carbon atoms in graphene. Spectroscopic results evidence that deuterium is predominantly incorporated in grain boundaries accompanied by rippling and etching of graphene, the latter effect being more pronounced at higher temperatures. Desorption experiments show that hydrogen (deuterium) incorporation is not completely reversible due to the damage induced in the graphene layer through the hydrogen adsorption/desorption cycle.