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

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) In0.05Ga0.95N/Al0.1Ga0.9N 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 cm2 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.