Exciton Effects in Low-Barrier GaN/AlGaN Quantum Wells

Cretı̀, Arianna; Tobaldi, David Maria; Lomascolo, M.; Tarantini, Iolena; Esposito, Marco; Passaseo, A.; Tasco, V.

doi:10.1021/acs.jpcc.2c04118

Cited by 3 publications

(1 citation statement)

References 39 publications

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“…The following AlN interlayer (when present, with nominal thicknesses of 1.5 and 3 nm) and AlGaN epilayer of the heterostructure were then grown at the same temperature. 28 A schematic of the epitaxial film structure is shown in Fig. 1.…”

Section: Growth Of Gan/algan Heterostructuresmentioning

confidence: 99%

AlN interlayer-induced reduction of dislocation density in the AlGaN epilayer

Tobaldi,

Lajaunie,

Cretì

et al. 2024

CrystEngComm

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Section: Growth Of Gan/algan Heterostructuresmentioning

confidence: 99%

AlN interlayer-induced reduction of dislocation density in the AlGaN epilayer

Tobaldi,

Lajaunie,

Cretì

et al. 2024

CrystEngComm

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Impact of fin aspect ratio on enhancement of external quantum efficiency in single AlGaN fin light-emitting diodes pixels

Nikoobakht

Zong

Koksal

et al. 2023

Applied Physics Letters

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Previously, we showed within a sub-micron fin shape heterojunction, as current density increases, the non-radiative Auger recombination saturates mediated by the extension of the depletion region into the fin, resulting in a droop-free behavior. Here, we investigate the dependence of the fin aspect ratio (height to width ratio) on external quantum efficiency (EQE) of single n-AlGaN fin/p-GaN heterojunctions. Fins are arranged in an array format varying in width from 3000 to 200 nm. In this architecture, an n-metal contact is interfaced with the non-polar side facet of the fin. At a fixed current density, as the aspect ratio increases from 0.2 to 3 (the fin width reduces), we systematically observe an increase in the ultraviolet (UV) excitonic emission of the AlGaN fin and a 7× enhancement in the EQE. We explain this phenomenon by conserving the volume of the carrier depletion region within a fin. As the fin gets thinner, the base area of the depletion volume shrinks, whereas its height increases within the fin. This geometrical advantage allows a 200 nm wide fin to operate at 1/3rd the current density compared to a 3000 nm wide fin while generating a UV emission with a comparable power of 1 μW. These findings show additional parameters that can be used for developing brighter light sources, including the shape and aspect ratio of a heterojunction at the micro- or nano-scale.

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AlN interlayer-induced reduction of dislocation density in the AlGaN epilayer

Tobaldi,

Lajaunie,

Cretì

et al. 2024

Preprint

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The emerging ultrawide-bandgap AlGaN alloy system holds promise for the development of advanced materials in the next generation of power semiconductor and UV optoelectronic devices. Within this context, heterostructures based on III-nitrides are very popular in view of their applications as electronics and optoelectronics components. AlGaN-based deep UV emitters are gaining visibility for their disinfection capabilities. Likewise, high electron mobility transistors are attracting increasing attention owing to their superior electron transport which yields high-speed and high-power applications. Those devices are conventionally made of AlGaN/GaN heterostructures grown on foreign substrate. However, structural defects, including stress induced by a mismatch in unit cell parameters and the presence of dislocations, can not only decrease the efficiency of the light emitters (by facilitating the non-radiative recombination of electron-hole pairs), but also impede electron mobility within the two-dimensional electron gas at the AlGaN/GaN interface. Therefore, the significance of obtaining high-quality AlGaN layers becomes evident. Including a thin AlN interlayer between the GaN buffer layer and AlGaN is a possible answer to address these drawbacks. Not only we show that a thin AlN layer, approximately ≤ 3 nm in thickness, between the GaN buffer and AlGaN layers, is effective in decreasing the dislocation densities in the AlGaN layer. Still, this is responsible of an increase in the electron mobility of the resulting heterostructure compared to a classical AlGaN/GaN heterostructure.

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Exciton Effects in Low-Barrier GaN/AlGaN Quantum Wells

Cited by 3 publications

References 39 publications

AlN interlayer-induced reduction of dislocation density in the AlGaN epilayer

AlN interlayer-induced reduction of dislocation density in the AlGaN epilayer

Impact of fin aspect ratio on enhancement of external quantum efficiency in single AlGaN fin light-emitting diodes pixels

AlN interlayer-induced reduction of dislocation density in the AlGaN epilayer

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