High transparency of AgZn-Ni solid-solution ohmic contacts for GaN-based ultraviolet light-emitting diodes

Abstract

AgZn-Ni solid-solution scheme has been investigated to produce transparent ohmic contacts for ultraviolet (UV) light-emitting diodes (LEDs). The AgZn-Ni solid-solution contacts annealed at 430 °C for 1 min in air show high transmittance of 67%-69% at 340 nm, which is much better than that (53%) of the conventional NiAu contact. The annealed contacts give specific contact resistance of 8.2× 10-5 and 4.8× 10-5 Ω cm2. Further, near UV LEDs (300×300 μ m2) made with the annealed contact layers produce a forward-bias voltage of 3.32-3.46 V at 20 mA. Possible explanations are given to describe the annealing-induced improvement of the ohmic behaviors of the AgZn-Ni solid-solution contacts. © 2005 American Institute of Physics.