Highly efficient transverse-electric-dominant ultraviolet-C emitters employing GaN multiple quantum disks in AlN nanowire matrix

Ram Chandra Subedi, Jung Wook Min, Somak Mitra, Kuang Hui Li, Idris Ajia, Edgars Stegenburgs, Dalaver H. Anjum, Michele Conroy, Kalani Moore, Ursel Bangert, Iman S. Roqan, Tien Khee Ng, Boon S. Ooi

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

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.

Original languageEnglish
Title of host publicationGallium Nitride Materials and Devices XVI
EditorsHiroshi Fujioka, Hadis Morkoc, Ulrich T. Schwarz
PublisherSPIE
ISBN (Electronic)9781510642072
DOIs
Publication statusPublished - 2021
EventGallium Nitride Materials and Devices XVI 2021 - Virtual, Online, United States
Duration: 6 Mar 202111 Mar 2021

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume11686
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceGallium Nitride Materials and Devices XVI 2021
Country/TerritoryUnited States
CityVirtual, Online
Period6/03/2111/03/21

Keywords

  • Deep-ultraviolet emission
  • GaN quantum disks
  • epitaxial growth
  • quantum confinement
  • transverse-electric-emission

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