Effects of the ultra-high vacuum heating on oxidized germanene

Suzuki, Seiya   ; Katsube, Daiki*; Yano, Masahiro   ; Tsuda, Yasutaka   ; Terasawa, Tomoo   ; Asaoka, Hidehito  ; Yuhara, Junji*; Yoshigoe, Akitaka 

Germanene is a two-dimensional (2D) sheet of germanium (Ge) with a honeycomb lattice. Recent theoretical studies have predicted several interesting electronic properties of germanene, such as 2D topological insulators. However, unlike graphene, germanene is easily oxidized in air, making it difficult to realize electrical devices based on germanene. To overcome the drawback of the chemical stability of germanene, it is necessary to understand how germanene is oxidized. Therefore, we started to study germanene and discovered an interesting phenomenon: oxidized germanene can be restored to good quality germanene simply by heating it in ultra-high vacuum (UHV). X-ray photoelectron spectroscopy spectra and low energy electron diffraction patterns indicate that the oxidized germanene is fully recovered after heating at 500 degrees Celsius. The detailed mechanism of the recovery will be discussed in the presentation.