Degradation reduction and stability enhancement of p-type graphene by RhCl3 doping

Three dopants, HNO3, AuCl3, and RhCl3 have been employed to fabricate p-type graphene layers with varying doping concentration and subsequently compare their structural, optical, and electrical properties. By RhCl3 doping, the sheet resistance is most stable as time elapses and the Raman frequency/work function (thus Dirac point) are most doping-sensitive without big degradation of transmittance and hole mobility. The CC/CC bonds intensity ratio (ICC/ICC) in the C 1s X-ray photoelectron spectra increases in all doped samples with the change being largest by RhCl3 doping, another evidence for the p-type doping by electron transfer from graphene sheets to the adsorbates. The largest ICC/ICC ratio may indicate the C atoms are most fully double-bonded even though a lot of electrons are leaked out from graphene, thereby making the graphene layer least defective, consistent with the minimized reduction of the transmittance and the hole mobility by RhCl3 doping.