title: Visible Color Tunable Emission in Three-Dimensional Light Emitting Diodes by MgO Passivation of Pyramid Tip.
abstract: We demonstrated visible color tunable three-dimensional (3D) pyramidal light emitting diodes by depositing the MgO on and near the tip of the pyramid as an insulating layer. Here, we show that the degradation of the materials (i.e., p-GaN) crystallinity and the built-in electric field due to the nanoscale geometry of the tip region is responsible for the large leakage current observed in LEDs. Confocal scanning electroluminescence microscopy images clearly showed that the intensity of the light emitted out of the side facet of the pyramid is much higher than that of the light extracted out of the tip surface, indicating that the MgO layer prohibited the carrier injection to the MQWs layer, suppressing the leakage occurring at or near the tip region of the pyramids. The color range of the LEDs can be also tuned by using the MgO layer, a blue-shift by 10.3 nm in the wavelength. This technique is simple and scalable, providing a promising solution for developing 3D pyramidal LEDs with low leakage current and controllable light emission.
authors.affiliation: Department of Materials Science Engineering, KIST-UNIST-Ulsan Center for Convergent Materials, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798, Republic of Korea.
authors.forename: Ji-Hyun
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Materials Science Engineering, KIST-UNIST-Ulsan Center for Convergent Materials, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798, Republic of Korea.
authors.forename: Byeong Uk
authors.initials: BU
authors.lastname: Ye
authors.affiliation: Department of Materials Science Engineering, KIST-UNIST-Ulsan Center for Convergent Materials, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798, Republic of Korea.
authors.forename: Joonmo
authors.initials: J
authors.lastname: Park
authors.affiliation: Department of Materials Science and Engineering, Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH) , Pohang, Gyeongbuk 790-784, Republic of Korea.
authors.forename: Chul Jong
authors.initials: CJ
authors.lastname: Yoo
authors.affiliation: Department of Materials Science and Engineering, Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH) , Pohang, Gyeongbuk 790-784, Republic of Korea.
authors.forename: Buem Joon
authors.initials: BJ
authors.lastname: Kim
authors.affiliation: UNIST Central Research Facilities (UCRF), Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798, Korea.
authors.forename: Hu Young
authors.initials: HY
authors.lastname: Jeong
authors.affiliation: UNIST-OLYMPUS BIOMED IMAGING CENTER(UOBC), Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798, Republic of Korea.
authors.forename: Jin-Hoe
authors.initials: JH
authors.lastname: Hur
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH) , Pohang, Gyeongbuk 790-784, Republic of Korea.
authors.forename: Jong Kyu
authors.initials: JK
authors.lastname: Kim
authors.affiliation: Department of Materials Science and Engineering, Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH) , Pohang, Gyeongbuk 790-784, Republic of Korea.
authors.forename: Jong-Lam
authors.initials: JL
authors.lastname: Lee
authors.affiliation: Department of Materials Science Engineering, KIST-UNIST-Ulsan Center for Convergent Materials, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798, Republic of Korea.
authors.forename: Jeong Min
authors.initials: JM
authors.lastname: Baik
keywords: MgO; color tunable; current path control; light emitting diodes; pyramid