AlGaInP thin-film LED with omni-directionally reflector and ITO transparent conducting n-type contact

In this paper a novel AlGaInP thin-film light-emitting diode (LED)with omni-directionally reflector (ODR) and transparent conductingindium tin oxide (ITO) n-type contact structure is proposed, andfabrication process is developed. This reflector is realized with thecombination of a low-refractive-index dielectric layer and a highreflectivity metal layer. This allows the light emitted or internallyreflected downwardly towards the GaAs substrate at any angle ofincidence to be reflected towards the top surface of the chip. ITOn-type contact is used for anti-reflection and current spreadinglayers on the ODR-LED with ITO. The sheet resistance of the ITO films(95 nm) deposited on n-ohmic contact of ODR-LED is of the order23.5${\Omega}$/$\Box$ with up to 90% transmittance (above 92% for 590--770 nm) in the visible region of the spectrum. The opticaland electrical characteristics of the ODR-LED with ITO are presentedand compared to conventional AS-LED and ODR-LED without ITO. It isshown that the light output from the ODR-LED with ITO at forwardcurrent 20 mA exceeds that of AS-LED and ODR- ED without ITO byabout a factor of 1.63 and 0.16, respectively. A favourable luminousintensity of 218.3 mcd from the ODR- ED with ITO (peak wavelength620 nm) could be obtained under 20 mA injection, which is 2.63times and 1.21 times higher than that of AS-LED and ODR-LED withoutITO, respectively.