Excitonic localization in AlN-rich AlxGa1−xN/AlyGa1−yN multi-quantum-well grain boundaries

Ajia, Idris A.; Edwards, P. R.; Liu, Z.; Yan, Jheng-Tai; Martin, Robert; Roqan, Iman S.

doi:10.1063/1.4896681

Cited by 42 publications

(26 citation statements)

References 30 publications

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“…In contrast with Ref. 24, we can exclude grain boundaries as the cause of this effect as we do not observe an increased density of dislocations along the edges of the spiral hillocks in these samples. 26 Fig .…”

Section: à2contrasting

confidence: 43%

“…The energy variation in sample C is due to a higher GaN incorporation at the step edges which results in a lower bandgap compared to the surrounding material and explains the increase in the NBE intensity. 18,23 The variation in the emission energy between the different domains in samples A and B could be due to exciton localization at grain boundaries 24 or compositional inhomogeneity. We have performed SE imaging, CL hyperspectral imaging, and ECCI on the same sample area (Fig.…”

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confidence: 99%

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Spatial clustering of defect luminescence centers in Si-doped low resistivity Al0.82Ga0.18N

Kusch

Nouf-Allehiani

Mehnke

et al. 2015

Applied Physics Letters

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A series of Si-doped AlN-rich AlGaN layers with low resistivities was characterized by a combination of nanoscale imaging techniques. Utilizing the capability of scanning electron microscopy to reliably investigate the same sample area with different techniques, it was possible to determine the effect of doping concentration, defect distribution, and morphology on the luminescence properties of these layers. Cathodoluminescence shows that the dominant defect luminescence depends on the Si-doping concentration. For lower doped samples, the most intense peak was centered between 3.36 eV and 3.39 eV, while an additional, stronger peak appears at 3 eV for the highest doped sample. These peaks were attributed to the (VIII-ON)2− complex and the VIII3− vacancy, respectively. Multimode imaging using cathodoluminescence, secondary electrons, electron channeling contrast, and atomic force microscopy demonstrates that the luminescence intensity of these peaks is not homogeneously distributed but shows a strong dependence on the topography and on the distribution of screw dislocations.

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Section: à2contrasting

confidence: 43%

mentioning

confidence: 99%

Spatial clustering of defect luminescence centers in Si-doped low resistivity Al0.82Ga0.18N

Kusch

Nouf-Allehiani

Mehnke

et al. 2015

Applied Physics Letters

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“…Further advances in the field of DUV optoelectronics are hindered by other issues, such as the difficulty in developing new cost‐effective material production and fabrication methods that could replace the expensive and high vacuum‐based technologies presently in use. Thus, as DUV‐WBGS based devices tend to be prohibitively expensive, they are difficult to produce on a large scale . Moreover, the defects in the interface between layers, such as lattice mismatch and dislocation defects, significantly hinder the performance of DUV devices .…”

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confidence: 99%

Novel P‐Type Wide Bandgap Manganese Oxide Quantum Dots Operating at Deep UV Range for Optoelectronic Devices

Mitra

Pak

Alaal

et al. 2019

Advanced Optical Materials

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in a wide range of industrial applications, such as homeland security, medical diagnostics, food curing, sanitation, chemical and biological threat detection, space-tospace communications, missile detection, military surveillance, target detection and acquisition, transparent thin-film transistors, solar cells, white lighting, sterilization, medical treatment, and touch display panels. [1][2][3][4][5][6][7] For example, the most commercial DUV photodetectors are produced using UV-enhanced narrow bandgap semiconductors, mainly Si-based photodetector. [8,9] However, the narrow bandgap materials are ineffective in rejecting signals in the UV−vis−IR spectral region, making them unsuitable for DUV applications. Thus, high-quality DUV WBGSs are still needed to produce high-performance DUV optoelectronic devices. In each of the aforementioned fields, scientists and industry practitioners are looking to overcome different challenges. There is a growing demand for both p-type and n-type WBGSs that possess good stability and conductivity. The main obstacle to the achievement of this goal stems from the lack of p-type wide bandgap materials operating in the DUV range below 300 nm (i.e., >4.1 eV) that exhibit good p-type stability. Currently, the p-type materials having bandgap in the UV-A range (such as p-type GaN, Cu 2 O, and SnO) are utilized in DUV optoelectronics, which severely downgrade device performance, as their bandgaps are limited to the UV-A-to-visible spectral region (320-400 nm). [10,11] Moreover, though n-type WBGSs (e.g., ZnO, Ga 2 O 3 , and AlGaN) with good conductivity and stability can operate in the UV and DUV range (280−390 nm), it is not possible to convert them to a p-type material with good stability and conductivity due to their intrinsic electronic properties. [2,6,[11][12][13][14][15][16] Consequently, no highly stable conductive p-type DUV WBGS operating in both UV-B and UV-C region presently exists. [17] Further advances in the field of DUV optoelectronics are hindered by other issues, such as the difficulty in developing new cost-effective material production and fabrication methods that could replace the expensive and high vacuum-based technologies presently in use. Thus, as DUV-WBGS based devices tend Wide bandgap semiconductor (WBGS)-based deep UV (DUV) devices lag behind those operating in the visible and IR range, as no stable p-type WBGS that operates in the DUV region (<300 nm) presently exists. Here, solutionprocessed p-type manganese oxide WBGS quantum dots (MnO QDs) are explored. Highly crystalline MnO QDs are synthesized via femtosecond-laser ablation in liquid. The p-type nature of these QDs is demonstrated by Kelvin probe and field effect transistor measurements, along with density functional theory calculations. As proof of concept, a high-performance, self-powered, and solar-blind Schottky DUV photodetector based on such QDs is fabricated, which is capable of detecting under ambient conditions. The carrier collection efficiency is enhanced by asymmetric electrode structure, leadi...

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“…Both samples exhibit the known s-shape dependence of NBE energy on temperature typical of exciton localization in III-nitride MQW structures. [30][31][32] There is an initial redshift in the energy peak as temperature increases from 5 K to ~60 K, indicating carrier relocalization to lower energy states. Subsequently, a blueshift commences within the 60-110 K temperature range.…”

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confidence: 99%

GaN/AlGaN multiple quantum wells grown on transparent and conductive (-201)-oriented β-Ga2O3 substrate for UV vertical light emitting devices

Ajia

Yamashita²,

Lorenz

et al. 2018

Applied Physics Letters

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GaN/AlGaN multiple quantum wells (MQWs) are grown on a 2 01-oriented β-Ga2O3 substrate. The optical and structural characterizations of the MQW structure are compared with a similar structure grown on sapphire. Scanning transmission electron microscopy and atomic force microscopy images show that the MQW structure exhibits higher crystalline quality of welldefined quantum wells, when compared to a similar structure grown on sapphire. X-ray diffraction rocking curve and photoluminescence excitation analyses confirm a lower density of dislocation defects in the sample grown on β-Ga2O3 substrate. Detailed analysis of time-integrated and time

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Excitonic localization in AlN-rich AlxGa1−xN/AlyGa1−yN multi-quantum-well grain boundaries

Abstract: KAUST Repository

Cited by 42 publications

References 30 publications

Spatial clustering of defect luminescence centers in Si-doped low resistivity Al0.82Ga0.18N

Spatial clustering of defect luminescence centers in Si-doped low resistivity Al0.82Ga0.18N

Novel P‐Type Wide Bandgap Manganese Oxide Quantum Dots Operating at Deep UV Range for Optoelectronic Devices

GaN/AlGaN multiple quantum wells grown on transparent and conductive (-201)-oriented β-Ga2O3 substrate for UV vertical light emitting devices

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