Publications

Role of humidity in oxidation of ultrathin GaSe

Kowalski, Brian M.; Manz, Noah; Bethke, Donald T.; Shaner, Eric A.; Serov, Alexey; Kalugin, Nikolai G.

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 with further decompositions of these compounds to Ga2O3, SeO2, and amorphous selenium.