Enhanced Ultraviolet Random Lasing from Au/MgO/ZnO Heterostructure by Introducing p-Cu 2 O Hole-Injection Layer.

Ultraviolet light-emitting devices (LEDs) were fabricated on the basis of Au/MgO/ZnO metal/insulator/semiconductor (MIS) heterostructures. By introducing a thermally oxidized p-type Cu2 O hole-injection layer into this MIS structure, enhanced ultraviolet electroluminescence (EL) and random lasing with reduced threshold injection current are achieved. The enhancement mechanism is attributed to effective hole transfer from p-Cu2 O to i-MgO under forward bias, which increases the initial carrier concentration of MgO dielectric layer and further promotes "impact-ionization" effect induced carrier generation and injection. The current study proposes a new and effective route to improve the EL performance of MIS junction LEDs via introducing extrinsic hole suppliers.