The characterization of AlGaN nanowires prepared via chemical vapor deposition

Jiang, Renjie; Meng, Xianquan

doi:10.1007/s10854-019-01997-4

Cited by 6 publications

(5 citation statements)

References 28 publications

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“…Moreover, all peaks were deconvoluted, using Voigt multipeaks and a Shirley background. In figure 2(c), we show the spectrum N 1 s that is the result of convolution of two main component peaks centered at BE of 397.0 eV (N-Al bond) and 398.3 eV (N-Ga bond), showing a quite large area ratio of N-Al to N-Ga, in agreement with previously reported data for AlGaN with similar or even lower Al content [32,33], probably due to a slightly excess of Al content in the top most surface layer. In figure 2(d), we show the Al 2p spectrum that can be reproduced by two component peaks corresponding to Al-N bonds at a BE = 73.4 eV and Al-O bonds at 74.5 eV, the area ratio Al-O/Al-N being about 0.17.…”

Section: Xps Characterizationsupporting

confidence: 90%

Field emission from AlGaN nanowires with low turn-on field

Giubileo

Bartolomeo²,

Zhong³

et al. 2020

Nanotechnology

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We fabricate AlGaN nanowires by molecular beam epitaxy and we investigate their field emission properties by means of an experimental setup using nano-manipulated tungsten tips as electrodes, inside a scanning electron microscope. The tip-shaped anode gives access to local properties, and allows collecting electrons emitted from areas as small as 1µm 2 . The field emission characteristics are analysed in the framework of Fowler-Nordheim theory and we find a field enhancement factor as high as β = 556 and a minimum turn-on field 𝐸 𝑡𝑢𝑟𝑛−𝑜𝑛 = 17 V/µm for a cathode-anode separation distance 𝑑 = 500 nm. We show that for increasing separation distance, 𝐸 𝑡𝑢𝑟𝑛−𝑜𝑛 increases up to about 35 V/µm and β decreases to 100 at 𝑑 = 1600 nm. We also demonstrate the time stability of the field emission current from AlGaN nanowires for several minutes. Finally, we explain the observation of modified slope of the Fowler-Nordheim plots at low fields in terms of non-homogeneous field enhancement factors due to the presence of protruding emitters.

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Section: Xps Characterizationsupporting

confidence: 90%

Field emission from AlGaN nanowires with low turn-on field

Giubileo

Bartolomeo²,

Zhong³

et al. 2020

Nanotechnology

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“…However, in the captured Ru 3p spectrum (Figure S3, Supporting Information), the peak at 463.0 eV is different from the typical peaks at 461.2 eV for Ru metal, which has been likely attributed to the presence of an oxidation state close to Ru(III) or Ru(IV). [ 31 ] In N 1s (Figure 1f) spectra of AlGaN:Ru NWs and bare AlGaN NWs, the peaks at 397.1 and 398.0 eV can be consistent with the value of AlN and GaN bonds respectively, [ 32 ] and the 398.6 eV, which does not appear in N 1s spectrum of bare AlGaN NWs, is assigned to RuN bond. [ 33 ] The XPS analysis unambiguously prove the strong interaction between Ru and AlGaN NWs.…”

Section: Resultsmentioning

confidence: 80%

Highly Uniform, Self‐Assembled AlGaN Nanowires for Self‐Powered Solar‐Blind Photodetector with Fast‐Response Speed and High Responsivity

Wang

Huang

Liu

et al. 2020

Advanced Optical Materials

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Searching for power‐independent, compact, and highly environment‐sensitive photodetectors is a critical step towards the realization of next‐generation energy‐efficient and sustainable integrated optoelectronic systems. Particularly, the deep ultraviolet (UV) band, which has large photon energy, is extremely suitable for environment monitoring and invisible light communication application. Herein, the demonstration of self‐powered deep UV solar‐blind photodetectors in a photoelectrochemical (PEC) cell configuration is reported, adopting wide bandgap n‐type aluminum gallium nitride (AlGaN) nanowires as photoelectrode. After decorating nanowires with noble metal ruthenium (Ru), the constructed solar‐blind PEC photodetectors exhibited excellent responsivity of 48.8 mA W‐1, fast response speed (rise time of 83 ms and decay time of 19 ms) with large photocurrent density of 55 μA cm‐2 at 254 nm illumination. Such superior performance can be attributed to, firstly and foremost, the successful synthesis of highly uniform and defect‐free n‐type AlGaN nanowires which ensures efficient photogeneration via effective light‐harvesting, and secondly, the boosted carrier separation and collection efficiency through Ru decoration. This novel nanoarchitecture enables deep UV photodetection to work stably with low energy consumption, intriguingly, opening the possibility for the development of high‐performance PEC photodetectors based on group III‐nitride semiconductors covering the entire spectral range from infrared to deep UV.

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“…NWs can be grown through the VLS technique, with the assistance of a catalyst. In this method, the NWs grow in an anisotropic manner at a liquid-solid interface when the liquid metal catalyst (e.g., Ni or Au for AlGaN NWs) adsorbs a vapor, followed by segregation at the point of supersaturation to form the NWs in the solid phase form [40], [41]. However, VLS growth requires a specific temperature range which depends on the catalyst and the range in which it is most thermodynamically stable [40].…”

Section: Vlsmentioning

confidence: 99%

AlGaN nanowire deep ultraviolet light emitting diodes with graphene electrode

Parimoo

Zhang

Vafadar

et al. 2022

Applied Physics Letters

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Despite graphene being an attractive transparent conductive electrode for semiconductor deep ultraviolet (UV) light emitting diodes (LEDs), there have been no experimental demonstrations of any kind of semiconductor deep UV LEDs using a graphene electrode. Moreover, although aluminum gallium nitride (AlGaN) alloys in the format of nanowires are an appealing platform for surface-emitting vertical semiconductor deep UV LEDs, in particular, at short wavelengths, there are few demonstrations of AlGaN nanowire UV LEDs with a graphene electrode. In this work, we show that transferred graphene can serve as the top electrode for AlGaN nanowire deep UV LEDs, and devices emitting down to around 240 nm are demonstrated. Compared to using metal, graphene improves both the light output power and external quantum efficiency. Nonetheless, devices with a graphene electrode show a more severe efficiency droop compared to devices with metal. Here, we attribute the heating effect associated with the large contact resistance to be the major reason for the severe efficiency droop in the devices with a graphene electrode. Detailed scanning electron microscopy and Raman scattering experiments suggest that the nanowire height nonuniformity is the main cause for the large contact resistance; this issue could be potentially alleviated by using nanowires grown by selective area epitaxy that is able to produce nanowires with uniform height. This work, therefore, not only demonstrates the shortest wavelength LEDs using a graphene electrode but also provides a viable path for surface-emitting vertical semiconductor deep UV LEDs at short wavelengths.

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The characterization of AlGaN nanowires prepared via chemical vapor deposition

Cited by 6 publications

References 28 publications

Field emission from AlGaN nanowires with low turn-on field

Field emission from AlGaN nanowires with low turn-on field

Highly Uniform, Self‐Assembled AlGaN Nanowires for Self‐Powered Solar‐Blind Photodetector with Fast‐Response Speed and High Responsivity

AlGaN nanowire deep ultraviolet light emitting diodes with graphene electrode

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