Fabrication of GaN LEDs for Optical Communications

In this paper we report on the device fabrication and characterisation of InGaN/GaN multiple quantum well LEDs on sapphire substrates. Contact with the pGaN is made through a current spreading layer consisting of semi-transparent metal. IV curves and electroluminescence spectra have been measured. Devices that showed non-rectifying behaviour have been investigated and it is suggested that metal migration along defect tubes is the likely cause of these failures. It is recommended to use lower alloying temperatures for the p-contact metallisation in order to avoid this type of failure.