Low Resistance and Highly Reflective Sb-Doped SnO_2/Ag Ohmic Contacts to p-Type GaN for Flip-Chip LEDs

摘要

We have investigated high-quality Sb-doped SnO_2/Ag ohmic contacts to p-GaN for use in flip-chip light emitting diodes (LEDs). The Sb-doped SnO_2 /Ag contacts produce specific contact resistances of approx 10~(-4) OMEGA cm_2 upon annealing at 430 and 530 deg C for 1 min in air. It is shown that InGaN blue LEDs fabricated with the Sb-doped SnO_2 /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 SnO_2 /Ag contact layers show higher light output power compared with the LEDs with the Ag contacts