Nitride-based near-ultraviolet LEDs with an ITO transparent contact

Abstract

Indium tin oxide (ITO) (2300 nm) and Ni (5 nm)/Au (10 nm) films were deposited onto glass substrates, p-GaN layers, n +-InGaN/GaN short-period-superlattice (SPS) structures and near-ultraviolet (near-UV) In 0.05Ga 0.95N/Al 0.1Ga 0.9N light emitting diodes (LEDs). It was found that ITO on n +-SPS structure could provide us an extremely high transparency (i.e. 86.5% at 400 nm) and a reasonably small 1.2×10 −3 Ω cm 2 specific contact resistance. It was also found that, at 20 mA, the forward voltage of the near-UV LED with ITO on n +-SPS upper contact was 3.13 V, which is exactly the same as that of the near-UV LED with Ni/Au on n +-SPS upper contact. Furthermore, it was found that we could achieve a 36% larger output power by using such an ITO on n +-SPS upper contact.