Graphene defect formation by extreme ultraviolet generated photoelectrons

TL;DR

This study investigates how low-energy photoelectrons generated by EUV radiation induce defect formation in graphene, revealing that valence band photoelectrons significantly contribute to damage without notable chemical reactions with residual water.

Contribution

It demonstrates that valence band photoelectrons are a key factor in defect formation in graphene during EUV irradiation, expanding understanding of radiation-induced damage mechanisms.

Findings

E-beam irradiation causes defect formation evidenced by Raman D peak.

Graphene undergoes amorphization with increased irradiation dose.

Water partial pressure has minimal effect on defect formation.

Abstract

We have studied the effect of photoelectrons on defect formation in graphene during extreme ultraviolet (EUV) irradiation. Assuming the major role of these low energy electrons, we have mimicked the process by using low energy primary electrons. Graphene is irradiated by an electron beam with energy lower than 80 eV. After e-beam irradiation, it is found that the D peak, I(D), appears in the Raman spectrum, indicating defect formation in graphene. The evolution of I(D)/I(G) follows the amorphization trajectory with increasing irradiation dose, indicating that graphene goes through a transformation from microcrystalline to nanocrystalline and then further to amorphous carbon. Further, irradiation of graphene with increased water partial pressure does not significantly change the Raman spectra, which suggests that, in the extremely low energy range, e-beam induced chemical reactions between residual water and graphene is not the dominant mechanism driving defect formation in graphene. Single layer graphene, partially suspended over holes was irradiated with EUV radiation. By comparing with the Raman results from e-beam irradiation, it is concluded that the photoelectrons, especially those from the valence band, contribute to defect formation in graphene during irradiation.