A MIIIM diode and method of fabricating are disclosed. In one aspect, the MIIIM diode comprises a first metal electrode, a first region comprising a first insulator material having an interface with the first metal electrode, a second region comprising a second insulator material having an interface with the first insulator material, a third region comprising a third insulator material having an interface with the second insulator material, and a second metal electrode having an interface with the third insulator material. At least one of the first, second, or third insulator materials is lanthanum oxide.