On the impact of a metal–insulator–semiconductor structured n-electrode for AlGaN-based DUV LEDs

Abstract

In this work, a 280 nm AlGaN-based deep ultraviolet light-emitting diode (DUV LED) with a metal–insulator–semiconductor (MIS) structured n-electrode is fabricated and studied. The S i O 2 insulator layer is adopted to form the MIS structure by using an atomic layer deposition system. After adopting the MIS-structured n-electrode, the S i O 2 intermediate layer enables electron affinity for the contact metal to be higher than the conduction band of the n-AlGaN layer, which favors the electrons to be injected into the n-AlGaN layer by intraband tunneling rather than thermionic emission. Moreover, the thin S i O 2 insulator can share the applied bias, which makes the n-AlGaN layer surface less depleted and thus further facilitates the electron injection. The improved electron injection capability at the metal–semiconductor interface helps reduce the contact resistance and increase electron concentration in the active region, which then improves external quantum efficiency and wall-plug efficiency for the proposed DUV LED.