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Highly efficient transverse-electric-dominant ultraviolet-c emission employing GaN multiple quantum disks in AlN nanowires matrix

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conference contribution
posted on 2021-07-07, 13:47 authored by Ram Chandra Subedi, Jung-Wook Min, Somak Mitra, Kuang-Hui Li, Idris Ajia, Edgars Stegenburgs, Dalaver H. Anjum, Michele A. Conroy, Kalani Moore, URSEL BANGERTURSEL BANGERT, Iman S. Roqan, Tien Khee Ng, Boon S. Ooi
Heavy reliance on extensively studied AlGaN based light emitting diodes (LEDs) to replace environmentally hazardous mercury based ultraviolet (UV) lamps is inevitable. However, external quantum efficiency (EQE) for AlGaN based deep UV emitters remains poor. Dislocation induced nonradiative recombination centers and poor electron-hole wavefunction overlap due to the large polarization field induced quantum confined stark effect (QCSE) in “Al” rich AlGaN are some of the key factors responsible for poor EQE. In addition, the transverse electric polarized light is extremely suppressed in “Al”-rich AlGaN quantum wells (QWs) because of the undesired crossing over among the light hole (LH), heavy hole (HH) and crystal-field split-off (SH) states. Here, optical and structural integrities of dislocation-free ultrathin GaN quantum disk (QDisk) (~ 1.2 nm) embedded in AlN barrier (~ 3 nm) grown employing plasma-assisted molecular beam epitaxy (PAMBE) are investigated considering it as a novel nanostructure to realize highly efficient TE polarized deep UV emitters. The structural and chemical integrities of thus grown QDisks are investigated by high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). We, particularly, emphasize the polarization dependent photoluminescence (PL) study of the GaN Disks to accomplish almost purely TE polarized UV (~ 260 nm) light. In addition, we observed significantly high internal quantum efficiency (IQE) of ~ 80 %, which is attributed to the enhanced overlap of the electron-hole wavefunction in extremely quantum confined ultrathin GaN QDisks, thereby presenting GaN QDisks embedded in AlN nanowires as a practical pathway towards the efficient deep UV emitters.

History

Publication

Proc. SPIE Gallium Nitride Materials and Devices XVI;1168610

Publisher

SPIE: The International Society for Optics and Photonics

Note

peer-reviewed

Other Funding information

King Abdulaziz City for Science and Technology (KACST), King Abdullah University of Science and Technology(KAUST)

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Copyright 2021 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited

Language

English

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