Long lived high radiance LEDs for fibre optic communications systems

The degradation of high radiance LEDs has been characterised over a range of operating temperatures. It is shown that the decay is due to two independant mechanisms. The first mechanism relies on the movement of a charged species in the vicinity of the junction region. The second involves the breakdown of the p-side contact, followed by the diffusion of gold to the active region. The latter mechanism is expected to limit the device lifetime to approximately 106hours. An improved p-side metallisation is discussed.