Formation of Sb-doped SnO₂p-type ohmic contact for near-UV GaN -based LEDs by a CIO interlayer

A Cu-doped In2 O3 (CIO) interlayer was introduced to enhance the electrical and optical properties of Sb-doped SnO2 (ATO) p-type electrodes grown by pulsed laser deposition. CIO (2.5 nm) /ATO (250 nm) contacts become ohmic with specific contact resistance of 2.1× 10-3 cm2 and give transmittance of ∼81% at 400 nm, when annealed at 630°C for 1 min in air. Near-UV (400 nm) GaN -based light-emitting diodes (LEDs) fabricated with the CIO/ATO p-electrodes give forward-bias voltage of 3.91 V at injection current of 20 mA and show much higher output power compared to LEDs with conventional NiAu p-electrodes.