Molecular Beam Epitaxy of AlGaN Epilayers on Si for Vertical Deep Ultraviolet Light-Emitting Diodes

Zhang, Qihua; Parimoo, Heemal; Martel, Eli; Zhao, Songrui

doi:10.1149/2162-8777/aca2d9

Cited by 4 publications

(5 citation statements)

References 48 publications

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“…These surface characteristics are similar to our previous reports. 45,47,49 Nonetheless, for AlN epilayers grown directly on Si under similar conditions, the surface morphology is much worse; the droplet-free, smooth region is only ∼ mm 2 . The detailed comparison on the surface morphology as well as comments on the comparison can be found in Supporting Information.…”

Section: T H Imentioning

confidence: 99%

“…Recently, we have demonstrated nanowire template assisted AlN epilayers on low-cost Si substrates, including vertical AlGaN UV LED demonstrations. − However, the wafer-scale effect of the nanowire template on relaxing the lattice strain and electrical doping remains unclear. In this study, we carry out this critical and missing study: evaluating the role of the NW template, in the epitaxy of AlN and AlGaN epilayers on Si, using various characterization techniques including X-ray diffraction (XRD), Raman, photoluminescence (PL), current–voltage (I–V) characteristics, and electroluminescence (EL).…”

mentioning

confidence: 99%

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Nanowire Template Assisted Epitaxy of Ultrawide Bandgap III-Nitrides on Si: Role of the Nanowire Template

Zhang

Sivasundarampillai

Parimoo

et al. 2023

ACS Appl. Opt. Mater.

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Ultrawide bandgap III-nitrides, including AlN and high Al content AlGaN alloys, are of great importance for applications to deep ultraviolet photonics and radio frequency electronics. However, lack of suitable substrates remains a challenge. In this context, we investigate the molecular beam epitaxy of AlN and high Al content AlGaN epilayers on low-cost Si substrates using a nanowire template as an intermediate layer.First, the role of the nanowire template on the quality of AlN is elucidated. By comparing AlN epilayers grown with and without the nanowire template over a wide range of growth conditions, it is found that using the nanowire template can relax the tensile strain in the AlN epilayers, as well as improve the overall crystalline quality. Second, the role of the quality of the AlN epilayer on the quality of the p-AlGaN layer grown on top is further discussed. It is found that the improved quality of AlN, due to the use of the nanowire template, also transfers to the improvement of the p-type doping in the AlGaN epilayers grown on top, which further contributes to a drastic improvement on the electrical performance of AlGaN p-i-n diodes, i.e., a factor of 10 4 reduction on the reverse bias leakage current, as well as a 250× improvement on the light output, comparing the structure with and without using the nanowire template. The study potentially impacts the development of ultrawide bandgap III-nitrides on foreign substrates as well as low-cost ultrawide bandgap III-nitride template technologies for a wide range of electronic and photonic device applications.

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Section: T H Imentioning

confidence: 99%

mentioning

confidence: 99%

Nanowire Template Assisted Epitaxy of Ultrawide Bandgap III-Nitrides on Si: Role of the Nanowire Template

Zhang

Sivasundarampillai

Parimoo

et al. 2023

ACS Appl. Opt. Mater.

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“…Wide-bandgap materials of the III-N family are fundamental in the design and development of high-quality deep UV (DUV) devices. Aluminum-gallium nitride (AlGaN) has been extensively analyzed by epitaxial growth techniques such as metal−oxide chemical vapour deposition (MOCVD) [4] , molecular beam epitaxy (MBE) [5,6] , and liquid phase epitaxy (LPE) [7] . This high-quality growth has allowed us to understand the feasibility of Ⅲ-N properties, such as superior transport properties [8,9] and wide bandgap tunability [10,11] .…”

Section: Introductionmentioning

confidence: 99%

Metal-modulated epitaxy of Mg-doped Al_0.80In_0.20N-based layer for application as the electron blocking layer in deep ultraviolet light-emitting diodes

Solís-Cisneros,

Hernández-Gutiérrez,

Campos-González

et al. 2024

J. Semicond.

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This work reports the growth and characterization of p-AlInN layers doped with Mg by plasma-assisted molecular beam epitaxy (PAMBE). AlInN was grown with an Al molar fraction of 0.80 by metal-modulated epitaxy (MME) with a thickness of 180 nm on Si(111) substrates using AlN as buffer layers. Low substrate temperatures were used to enhance the incorporation of indium atoms into the alloy without clustering, as confirmed by X-ray diffraction (XRD). Cathodoluminescence measurements revealed ultraviolet (UV) range emissions. Meanwhile, Hall effect measurements indicated a maximum hole mobility of 146 cm2/(V∙s), corresponding to a free hole concentration of 1.23 × 1019 cm−3. The samples were analyzed by X-ray photoelectron spectroscopy (XPS) estimating the alloy composition and extracting the Fermi level by valence band analysis. Mg-doped AlInN layers were studied for use as the electron-blocking layer (EBL) in LED structures. We varied the Al composition in the EBL from 0.84 to 0.96 molar fraction to assess its theoretical effects on electroluminescence, carrier concentration, and electric field, using SILVACO Atlas. The results from this study highlight the importance and capability of producing high-quality Mg-doped p-AlInN layers through PAMBE. Our simulations suggest that an Al content of 0.86 is optimal for achieving desired outcomes in electroluminescence, carrier concentration, and electric field.

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“…Moreover, considering the beam flux monitor (BFM) has different sensitivities for sources at different positions, the Al fluxes were calibrated carefully using both the N supply ,, and monitoring surface optical reflection signals without the presence of N on our previously developed smooth, droplet- and crack-free AlN-on-NW template, ,,, to ensure that both Al sources produce a similar amount of Al at the surface, despite the difference in flux reading. In our chamber configuration, both Al sources have a similar flux, with around 5% variation in the flux reading, when a similar amount of Al is produced at the surface.…”

mentioning

confidence: 99%

Direct Observation of Al Migration Enhancement by Changing the Al and N Source Relative Position in the Molecular Beam Epitaxy of AlGaN Nanowires

Vafadar

Zhang

Zhao

2023

Crystal Growth & Design

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Aluminum (Al)-containing nitrides, including AlN, AlScN, and AlGaN, are emerging material platforms for futuregeneration photonic, electronic, ferroelectric, and multifunctional semiconductor devices. Nonetheless, the low Al migration mobility in a nitrogen environment is a notorious hindrance to obtaining high-quality Al-containing nitride epilayers. This is particularly the case for the epitaxy of Al-containing nitrides with radio frequency (RF) plasma-assisted molecular beam epitaxy (MBE), due to the use of relatively low substrate temperatures. As such, various approaches have been employed in promoting Al migration such as metal-modulated epitaxy (MME). Despite the progress, the effect of the relative position of the Al and N sources on the Al migration mobility has remained unclear. In this study, we show that MBE-grown AlGaN nanowires can be an effective probe to examine the effect of the Al and N source relative position on the Al migration mobility and demonstrate clearly that Al adatoms appear to be more mobile from the Al source that is far away from the N source, compared to those from the Al source that is near the N source. This study therefore can potentially impact the development of emerging Al-containing semiconductor devices by MBE. Moreover, the demonstrated correlated Al source dependent morphological and optical properties of AlGaN nanowires can naturally help the development of AlGaN-nanowire-based UV light-emitting diodes (LEDs) and lasers.

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Molecular Beam Epitaxy of AlGaN Epilayers on Si for Vertical Deep Ultraviolet Light-Emitting Diodes

Cited by 4 publications

References 48 publications

Nanowire Template Assisted Epitaxy of Ultrawide Bandgap III-Nitrides on Si: Role of the Nanowire Template

Nanowire Template Assisted Epitaxy of Ultrawide Bandgap III-Nitrides on Si: Role of the Nanowire Template

Metal-modulated epitaxy of Mg-doped Al_0.80In_0.20N-based layer for application as the electron blocking layer in deep ultraviolet light-emitting diodes

Direct Observation of Al Migration Enhancement by Changing the Al and N Source Relative Position in the Molecular Beam Epitaxy of AlGaN Nanowires

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Molecular Beam Epitaxy of AlGaN Epilayers on Si for Vertical Deep Ultraviolet Light-Emitting Diodes

Cited by 4 publications

References 48 publications

Nanowire Template Assisted Epitaxy of Ultrawide Bandgap III-Nitrides on Si: Role of the Nanowire Template

Nanowire Template Assisted Epitaxy of Ultrawide Bandgap III-Nitrides on Si: Role of the Nanowire Template

Metal-modulated epitaxy of Mg-doped Al0.80In0.20N-based layer for application as the electron blocking layer in deep ultraviolet light-emitting diodes

Direct Observation of Al Migration Enhancement by Changing the Al and N Source Relative Position in the Molecular Beam Epitaxy of AlGaN Nanowires

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Metal-modulated epitaxy of Mg-doped Al_0.80In_0.20N-based layer for application as the electron blocking layer in deep ultraviolet light-emitting diodes