Graphene/SiO₂/p-GaN diodes: An advanced economical alternative for electrically tunable light emitters

Advanced materials that combine novel functionality and ease of applicability are central to the development of light-emitting diodes (LEDs), which is of ever increasing commercial importance. Here a new metal-insulator-semiconductor (MIS) LED structure that combines economical fabrication with novel device properties is reported. The presented MIS-LED consists of a graphene electrode on p-GaN substrate separated by an insulating SiO₂ layer. It is found that the MIS-LED possesses a unique tunability of the electroluminescence spectra depending on the bias conditions. Tunnel injection from graphene into the p-GaN can explain the difference in luminescence spectra under forward and reverse bias. The demonstrated MIS-LED expands the use of graphene and also possibly allows the direct integration of light emitters with other circuit elements. Metal-insulator-semiconductor (MIS) light- emitting diodes (LEDs) consisting of a graphene electrode on p-GaN substrate separated by an insulating SiO₂ layer are reported. The novel MIS-LEDs have a unique tunability of the electroluminescence (EL) spectra depending on the bias conditions. The underlying mechanism can be interpreted as the tunneling of electrons and holes through the insulating layer in both polarities, which is different from the standard p-n junction model.