AlGaInP thin-film LED with omni-directionally reflector and ITO transparent conducting n-type contact
Zhang Jian-Ming(张剑铭)†, Zou De-Shu(邹德恕), Xu Chen(徐晨), Guo Wei-Ling(郭伟玲), Zhu Yan-Xu(朱彦旭), Liang Ting(梁庭), Da Xiao-Li(达小丽), Li Jian-Jun(李建军), and Shen Guang-Di(沈光地)
Beijing Optoelectronic Technology Laboratory, Beijing University of Technology, Beijing 100022, China
Abstract In this paper a novel AlGaInP thin-film light-emitting diode (LED) with omni-directionally reflector (ODR) and transparent conducting indium tin oxide (ITO) n-type contact structure is proposed, and fabrication process is developed. This reflector is realized with the combination of a low-refractive-index dielectric layer and a high reflectivity metal layer. This allows the light emitted or internally reflected downwardly towards the GaAs substrate at any angle of incidence to be reflected towards the top surface of the chip. ITO n-type contact is used for anti-reflection and current spreading layers 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 order 23.5${\Omega}$/$\Box$ with up to 90% transmittance (above 92% for 590--770 nm) in the visible region of the spectrum. The optical and electrical characteristics of the ODR-LED with ITO are presented and compared to conventional AS-LED and ODR-LED without ITO. It is shown that the light output from the ODR-LED with ITO at forward current 20 mA exceeds that of AS-LED and ODR- ED without ITO by about a factor of 1.63 and 0.16, respectively. A favourable luminous intensity of 218.3 mcd from the ODR- ED with ITO (peak wavelength 620 nm) could be obtained under 20 mA injection, which is 2.63 times and 1.21 times higher than that of AS-LED and ODR-LED without ITO, respectively.
Zhang Jian-Ming(张剑铭), Zou De-Shu(邹德恕), Xu Chen(徐晨), Guo Wei-Ling(郭伟玲), Zhu Yan-Xu(朱彦旭), Liang Ting(梁庭), Da Xiao-Li(达小丽), Li Jian-Jun(李建军), and Shen Guang-Di(沈光地) AlGaInP thin-film LED with omni-directionally reflector and ITO transparent conducting n-type contact 2007 Chinese Physics 16 3498
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