Electrically tunable, sustainable, and erasable broadband light absorption in graphene sandwiched in Al ₂ O ₃ oxides

Graphene has been used as an electrically tunable material for switchable devices. A large area fabrication of Al-doped ZnO/Al ₂ O ₃ /graphene/Al ₂ O ₃ /gold/silicon device was enabled by a spin-processible hydrophilic mono-layer graphene oxide. The graphene was obtained directly from graphene oxide during the atomic layer deposition without other extra steps. A significant shift of Raman frequency up to 360 cm ^-1 was observed from graphene in the fabricated device, indicating a structural change in graphene. The absorption from the device was tunable with a negative voltage applied on the Al-doped ZnO side. The generated absorption change was sustainable when the voltage was off and erasable when a positive voltage was applied. The sustainability of tuned optical property in the graphene under investigation can lead to a design of device with less power consumption and many other applications.