2 Search Results

The oxidation mechanisms of exfoliated Gallium Selenide (GaSe) are strongly influenced by humidity. We have observed that the presence of water molecules leads to formation of Ga₂O₃, SeO₂, and Se via sequence of intermediate reactions which include generation of aqueous solution of selenic acid. Raman spectra of GaSe flakes undergoing oxidation in a humidity-controlled environment reveal formation of selenic acid-related species causing Raman scattering signal in the regions around 830 cm^-1 and around 1230 cm^-1. This observation sheds light on the path of chemical reactions, going via an intermediate stage of formation of gallium hydroxide and selenium oxide-water complexes withmore » further decompositions of these compounds to Ga₂O₃, SeO₂, and amorphous selenium.« less

Graphene has established itself as a promising optoelectronic material. Many details of the photoresponse (PR) mechanisms in graphene in the THz-to-visible range have been revealed, however, new intricacies continue to emerge. Interface junctions, formed at the boundaries between parts of graphene with different number of layers or different stacking orders, and making connection between electrical contacts, provide another peculiar setup to establish PR. Here, we experimentally demonstrate an enhanced polarization sensitive photoelectric PR in graphene sheets containing interface junctions as compared to homogenous graphene sheets in the visible, infrared, and THz spectral regions. Our numerical simulations show that highly localizedmore » electronic states are created at the interface junctions, and these states exhibit a unique energy spectrum and enhanced probabilities for optical transitions. Here, the interaction of electrons from interface junction states with electromagnetic fields generates a polarization-sensitive PR that is maximal for the polarization direction perpendicular to the junction interface.« less