Low turn-on voltage AlGaInP LEDs using thermally evaporated transparent conducting Indium-Tin-Oxide (ITO)

Abstract

Low turn-on voltage AlGaInP/GaInP surface emitting LEDs have been achieved using a thermally evaporated transparent conducting Indium Tin Oxide (ITO) layer. The devices have lower forward series resistance (1-3) ohms compared to standard Au/Zn devices which have a series resistance greater than 5 ohms. The ITO/AlGaInP LEDs emit orange light, with a peak wavelength of 600 nm and full width at half maximum (FWHM) of 15 nm. A forward voltage of typically 1.70 V at 20 mA was obtained. Variations in the thicknesses of the cladding and GaAs cap layer thicknesses did not cause any significant change in the device turn-on voltages. Evidence of reduced junction heating has been observed.