Low resistance and highly reflective Sb-doped SnO2/Ag ohmic contacts to p-type GaN for flip-chip LEDs

We have investigated high-quality Sb-doped SnO2/Ag ohmic contacts to p-GaN for use in flip-chip light emitting diodes (LEDs). The Sb-doped SnO2/Ag contacts produce specific contact resistances of similar to 10(-4) Omega cm(2) upon annealing at 430 and 530 degrees C for 1 min in air. It is shown that InGaN blue LEDs fabricated with the Sb-doped SnO2/Ag contacts give a forward-bias voltage of 3.18 V at 20 mA, while LEDs with Ag contacts show 3.36 V. It is further shown that the LEDs made with the Sb-doped SnO2/Ag contact layers show higher light output power compared with the LEDs with the Ag contacts. (C) 2004 The Electrochemical Society.