Transparent electrode for UV light-emitting-diodes

We have investigated the transparent electrodes using indium tin oxide (ITO) for UV light-emitting diodes (LEDs). The carrier concentration of ITO was increased from 1.1×1018 to 1.5×1021cm-3 after annealing under N2 ambient at 600 °C. The fundamental absorption edge was also shifted to a shorter wavelength owing to the increase in carrier concentration, through the so-called the Burstein-Moss effect. The annealed ITO forms an ohmic contact with p-GaN with a specific contact resistance of 1.2×10-3Ωcm2. The light output power of a 350 nm LED with the annealed ITO contact is 1.2 times higher than that with a conventional Ni/Au contact. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)