Low-resistance and highly-reflective Zn-Ni solid solution/Ag ohmic contacts for flip-chip light-emitting diodes

We have investigated a Zn-Ni solid solution/Ag scheme for use in producing high-quality ohmic contacts for flip-chip light-emitting diodes (LEDs). The as-deposited contact shows nonlinear I-V characteristics. However, oxidizing the contacts at temperatures of 350-550 degreesC for 1 min in air ambient results in linear I-V behaviors, yielding specific contact resistances of 10(-4)-10(-5) Omega cm(2). In addition, LEDs are fabricated with the oxidized Zn-Ni solid solution/Ag contacts and Ag single contacts. The typical I-V characteristics of the LEDs with the annealed Zn-Ni solid solution (2.5 nm)/Ag (200 nm) p-type contact layers reveal a forward-bias voltage of 3.25 V at an injection current of 20 mA, which is much better than that of the LEDs with the Ag (200 nm) contact layers. (C) 2003 American Institute of Physics.