Lithuanian Journal of Physics article / Lietuvos fizikos žurnalo straipsnis

VOLUMETRIC CARRIER INJECTION IN InGaN QUANTUM WELL LIGHT EMITTING DIODES
Saulius Marcinkevičius^a, Rinat Yapparov^a, Tanay Tak^b, Jacob Ewing^b, Feng Wu^b, Steven P. DenBaars^b, Shuji Nakamura^b, and James S. Speck^b
^aDepartment of Applied Physics, KTH Royal Institute of Technology, AlbaNova University Center, 10691 Stockholm, Sweden
^bMaterials Department, University of California, Santa Barbara, CA USA 93106
Email: sm@kth.se

Received 30 October 2024; accepted 30 October 2024

InGaN/GaN quantum well (QW) light emitting diodes (LEDs) are essential components of solid-state lighting and displays. However, the efficiency of long wavelength (green to red) devices is inferior to that of blue LEDs. To a large degree, this occurs because the equilibration of injected holes between multiple QWs of the active region is hindered by GaN quantum confinement and polarization barriers. This drawback could be overcome by volumetric hole injection into all QWs through semipolar QWs present on the facets of V-defects that form at threading dislocations in polar GaN-based structures. In this work, we have tested the viability of this injection mechanism and studied its properties by time-resolved and near-field spectroscopy techniques. We have found that indeed the hole injection via the V-defects does take place, the mechanism is fast, and the hole spread from the V-defect is substantial, making this type of injection feasible for efficient long wavelength GaN LEDs.
Keywords: light emitting diodes, InGaN/GaN quantum wells, scanning near-field optical microscopy, carrier transport, V-defect

TŪRINĖ KRŪVININKŲ INJEKCIJA InGaN KVANTINIŲ DUOBIŲ ŠVIESOS DIODUOSE
Saulius Marcinkevičius^a, Rinat Yapparov^a, Tanay Tak^b, Jacob Ewing^b, Feng Wu^b, Steven P. DenBaars^b, Shuji Nakamura^b, James S. Speck^b

^aKTH Karališkasis technologijų institutas, Stokholmas, Švedija
^bKalifornijos universitetas, Santa Barbara, JAV

InGaN/GaN kvantinių duobių šviesos diodai yra esminiai kietojo kūno apšvietimo ir ekranų komponentai. Tačiau ilgojo matomos šviesos diapazono (nuo žalios iki raudonos) prietaisų efektyvumas yra prastesnis nei mėlynų šviesos diodų. Iš dalies tai atsitinka todėl, kad skylės nevienodai pasiskirsto tarp šviesos diodų aktyviosios srities kvantinių duobių. Šį netolygų pasiskirstymą lemia didelis kvantinių duobių gylis bei poliarizacijos barjerai tarp kvantinės duobės ir barjero sluoksnių. Šį trūkumą galbūt būtų galima apeiti naudojant tūrinę skylių injekciją per pusiau polines kvantines duobes, kurios formuojasi ant vadinamųjų V defektų, susidarančių ant dislokacijų polinėse GaN struktūrose. Šiame darbe ištyrėme, ar toks tūrinis skylių injekcijos mechanizmas yra iš principo galimas, ir išnagrinėjome jo savybes laikinės skyros ir artimojo lauko spektroskopijos metodais. Nustatėme, kad skylių injekcija per V defektus iš tiesų vyksta, šis mechanizmas yra greitas, o skylių difuzijos ilgis yra nemažas. Visa tai parodo, kad tūrinė skylių injekcija per V defektus turi didelių perspektyvų konstruojant efektyvius ilgų bangų GaN šviesos diodus.

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