Ultrathin GaN quantum wells in AlN nanowires for UV-C emission

Vermeersch, Rémy; Jacopin, Gwenolé; Castioni, Florian; García‐Cristóbal, A.; Cros, A.; Pernot, Julien; Daudin, B.

doi:10.1088/1361-6528/accaeb

Cited by 4 publications

(7 citation statements)

References 37 publications

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“…This model, however, can hardly explain the very high confinement energy corresponding to states that emit in the same structures at shorter wavelengths. Assuming that the emission photon energy of a GaN/AlN QW with a nominal thickness of 2 ML is about 4.8 eV [ 13 , 28 ], the observation of narrow lines around 5.1–5.2 eV suggests that the confinement energy generated due to the lateral quantum confinement reaches 300–400 meV. In fact, the observed emission photon energies of about 5.2 eV are much closer to the energy of photons emitted by a GaN/AlN QW with a nominal thickness of 1 ML, which is about 5.3 eV (radiation wavelengths in the range of 230–235 nm) [ 13 , 28 ].…”

Section: Resultsmentioning

confidence: 99%

“…Assuming that the emission photon energy of a GaN/AlN QW with a nominal thickness of 2 ML is about 4.8 eV [ 13 , 28 ], the observation of narrow lines around 5.1–5.2 eV suggests that the confinement energy generated due to the lateral quantum confinement reaches 300–400 meV. In fact, the observed emission photon energies of about 5.2 eV are much closer to the energy of photons emitted by a GaN/AlN QW with a nominal thickness of 1 ML, which is about 5.3 eV (radiation wavelengths in the range of 230–235 nm) [ 13 , 28 ]. Therefore, the corresponding exciton localization sites are relatively shallow potential wells with different exciton localization energies.…”

Section: Resultsmentioning

confidence: 99%

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Single-Exciton Photoluminescence in a GaN Monolayer inside an AlN Nanocolumn

et al. 2023

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GaN/AlN heterostructures with thicknesses of one monolayer (ML) are currently considered to be the most promising material for creating UVC light-emitting devices. A unique functional property of these atomically thin quantum wells (QWs) is their ability to maintain stable excitons, resulting in a particularly high radiation yield at room temperature. However, the intrinsic properties of these excitons are substantially masked by the inhomogeneous broadening caused, in particular, by fluctuations in the QWs’ thicknesses. In this work, to reduce this effect, we fabricated cylindrical nanocolumns of 50 to 5000 nm in diameter using GaN/AlN single QW heterostructures grown via molecular beam epitaxy while using photolithography with a combination of wet and reactive ion etching. Photoluminescence measurements in an ultrasmall QW region enclosed in a nanocolumn revealed that narrow lines of individual excitons were localized on potential fluctuations attributed to 2-3-monolayer-high GaN clusters, which appear in QWs with an average thickness of 1 ML. The kinetics of luminescence with increasing temperature is determined via the change in the population of localized exciton states. At low temperatures, spin-forbidden dark excitons with lifetimes of ~40 ns predominate, while at temperatures elevated above 120 K, the overlying bright exciton states with much faster recombination dynamics determine the emission.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Single-Exciton Photoluminescence in a GaN Monolayer inside an AlN Nanocolumn

et al. 2023

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“…Recently (in 2023), two research groups using PA MBE technology have joined the study of ML-thick GaN/AlN MQW structures emitting in the UVC range with e-beam pumping [ 115 , 116 ]. The first of them, headed by Daudin, is the leading scientific group that has developed a basic understanding of the PA MBE growth kinetics of III-N layers and associated heterostructures [ 117 , 118 ].…”

Section: Main Results Of Uvc Emission Using Electron Beam Pumpingmentioning

confidence: 99%

“…However, it should be noted that at energies above 20 keV, an ditional long-wavelength peak appeared at 340 nm, which was associated with the etration of a high-energy e-beam into the AlN buffer layer, in which it excites defe radiation (associated with carbon atoms and other defects). Recently (in 2023), two research groups using PA MBE technology have joined the study of ML-thick GaN/AlN MQW structures emitting in the UVC range with e-beam pumping [115,116]. The first of them, headed by Daudin, is the leading scientific group that has developed a basic understanding of the PA MBE growth kinetics of III-N layers and associated heterostructures [117,118].…”

Section: Medium-power Uvc Emitters (Up To 1 W)mentioning

confidence: 99%

Electron-Beam-Pumped UVC Emitters Based on an (Al,Ga)N Material System

2023

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Powerful emitters of ultraviolet C (UVC) light in the wavelength range of 230–280 nm are necessary for the development of effective and safe optical disinfection technologies, highly sensitive optical spectroscopy and non-line-of-sight optical communication. This review considers UVC emitters with electron-beam pumping of heterostructures with quantum wells in an (Al,Ga)N material system. The important advantages of these emitters are the absence of the critical problem of p-type doping and the possibility of achieving record (up to several tens of watts for peak values) output optical power values in the UVC range. The review consistently considers about a decade of world experience in the implementation of various UV emitters with various types of thermionic, field-emission, and plasma-cathode electron guns (sources) used to excite various designs of active (light-emitting) regions in heterostructures with quantum wells of AlxGa1−xN/AlyGa1−yN (x = 0–0.5, y = 0.6–1), fabricated either by metal-organic chemical vapor deposition or by plasma-activated molecular beam epitaxy. Special attention is paid to the production of heterostructures with multiple quantum wells/two-dimensional (2D) quantum disks of GaN/AlN with a monolayer’s (1 ML~0.25 nm) thickness, which ensures a high internal quantum efficiency of radiative recombination in the UVC range, low elastic stresses in heterostructures, and high-output UVC-optical powers.

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“…In addition, they carried out pioneering studies of segregation phenomena during the growth of GaN/AlN heterostructures, which determine the temperature dependences of the sharpness and symmetry of heterointerfaces in these structures [114]. In a recent work of this group [115], the fine structure of the CL spectra of GaN disks 1-4 ML thick in AlN nanowires was studied in order to control the emission wavelength of AlN nanowires. Particular attention in this work was paid to emission lines below 240 nm (which corresponds to 1 ML), which were assigned to the recombination of confined carriers in the incomplete QWs with a lateral size smaller or comparable to the 2.8 nm GaN Bohr exciton radius.…”

Section: Uvc-emitters Pumped By Thermionic E-gunsmentioning

confidence: 99%

Electron-Beam Pumped UVC-Emitters Based on (Al, Ga)N Material System

Jmerik¹,

Kozlovsky²,

Wang³

2023

Preprint

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Powerful emitters of the ultraviolet C (UVC) light in the wavelength range of 230-280nm are necessary for the development of effective and safe optical disinfection technologies, high-sensitive optical spectroscopy and non-line-of-sight optical communication. This review considers such UVC-emitters with electron-beam pumping of heterostructures with quantum wells in the (Al,Ga)N material system. The important advantages of these emitters include the absence of the critical problem of p-type doping and the possibility of achieving record (up to several tens of watts for peak values) output optical power values in the UVC range. The review consistently considers about a decade of world experience in the implementation of various UV emitters with various types of thermionic, field-emission, and plasma-cathode electron guns (sources) used to excite various designs of active (light-emitting) regions in heterostructures with quantum wells AlxGa1-xN/AlyGa1-yN (x = 0 − 0.5, y = 0.6 − 1) fabricated either by metal-organic chemical vapor deposition or by plasma-activated molecular beam epitaxy. Special attention is paid to the production of heterostructures with multiple quantum wells/two-dimensional(2D) quantum disks GaN/AlN with a monolayer (1ML ~ 0.25nm) thickness, which ensures a high internal quantum efficiency of radiative recombination in the UVC range, low elastic stresses in heterostructures, and a high output UVC-optical powers.

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Ultrathin GaN quantum wells in AlN nanowires for UV-C emission

Cited by 4 publications

References 37 publications

Single-Exciton Photoluminescence in a GaN Monolayer inside an AlN Nanocolumn

Single-Exciton Photoluminescence in a GaN Monolayer inside an AlN Nanocolumn

Electron-Beam-Pumped UVC Emitters Based on an (Al,Ga)N Material System

Electron-Beam Pumped UVC-Emitters Based on (Al, Ga)N Material System

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