Quantified hole concentration in AlGaN nanowires for high-performance ultraviolet emitters

Zhao, Chao; ElKabbash, Mohamed; Zhang, Huafan; Priante, Davide; Janjua, Bilal; Zhang, Daliang; Wei, Nini; Alhamoud, Abdullah A.; Shakfa, Mohammad Khaled; Ng, Tien Khee; Ooi, Boon S.

doi:10.1039/c8nr02615g

Cited by 24 publications

(15 citation statements)

References 74 publications

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“…Thus, it is clear that the one-by-one Hall measurement of single nanorods is probably the most accurate one. However, the method is mostly valid to nanorods or nanowires of brittle and low density, which requires challenging processing procedures [45]. In this case, Hall-effect measurement is enabled by Al-doped ZnO seed layer beneath ZnO nanorods as a conducting medium.…”

Section: Resultsmentioning

confidence: 99%

Mapping the structural, electrical, and optical properties of hydrothermally grown phosphorus-doped ZnO nanorods for optoelectronic device applications

et al. 2019

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The phosphorus-doped ZnO nanorods were prepared using hydrothermal process, whose structural modifications as a function of doping concentration were investigated using X-ray diffraction. The dopant concentration-dependent enhancement in length and diameter of the nanorods had established the phosphorus doping in ZnO nanorods. The gradual transformation in the type of conductivity as observed from the variation of carrier concentration and Hall coefficient had further confirmed the phosphorus doping. The modification of carrier concentration in the ZnO nanorods due to phosphorus doping was understood on the basis of the amphoteric nature of the phosphorus. The ZnO nanorods in the absence of phosphorus showed the photoluminescence (PL) in the range of the ultraviolet (UV) and visible regimes. The UV emission, i.e. near-band-edge emission of ZnO, was found to be red-shifted after the doping of phosphorus, which was attributed to donor-acceptor pair formation. The observed emissions in the visible regime were due to the deep level emissions that were aroused from various defects in ZnO. The Al-doped ZnO seed layer was found to be responsible for the observed near-infrared (NIR) emission. The PL emission in UV and visible regimes can cover a wide range of applications from biological to optoelectronic devices.

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Section: Resultsmentioning

confidence: 99%

Mapping the structural, electrical, and optical properties of hydrothermally grown phosphorus-doped ZnO nanorods for optoelectronic device applications

et al. 2019

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“…However, this constitutes a trade-off as the doping ionization efficiency reduces with increasing Al concentration, resulting in less free holes. In addition, we were able to achieve a hole concentration of 1.3 × 10 19 cm −3 with large injection current [34].…”

Section: Methodsmentioning

confidence: 90%

Enhanced electro-optic performance of surface-treated nanowires: origin and mechanism of nanoscale current injection for reliable ultraviolet light-emitting diodes

Priante

Tangi

Min

et al. 2018

Opt. Mater. Express

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Self-assembled nanowires are posed to be viable alternatives to conventional planar structures, including the nitride epitaxy for optoelectronic, electronic and nano-energy applications. In many cases, current injection and extraction at the nanoscopic scale are essential for marked improvement at the macroscopic scale. In this investigation, we study the mechanism of nanoscale current injection and the origin of improvement of the flow of charged carriers at the group-III nitride semiconductor surface and metal-semiconductor interfaces. Conductive atomic force microscopy (c-AFM) and Kelvin probe force microscopy (KPFM) enable a rapid analysis of the electrical and morphological properties of single and ensemble nanostructures. The surface potential and current injection of AlGaN nanowirebased LEDs are spatially mapped before and after surface treatment with KOH solution. Treated-nanowires showed an improved current spreading and increased current injection by nearly 10×, reduced sub-turn-on voltage (as low as 5 V), and smaller series resistance. The reduced contact potential confirms the lower semiconductor/metal barrier, thus enabling larger carriers flow, and correlates with the 15% increase in injection efficiency in macroscopic LEDs. The improvement leads to the normalization of nanoscale electrical conducting properties of UV AlGaN-based nanowire-LEDs and lays the foundation for the realization of practical nanowire-based device applications.

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“…2. Details of EIS measurements can be found in our previous articles [13,20]. The positive slope of the curve for n-InGaN/GaN NWs and the negative slope of the curve for the u-InGaN/p-GaN and p-InGaN/p-GaN NWs were due to successful Si and Mg doping, correspondingly.…”

Section: Methodsmentioning

confidence: 93%

“…The estimated ionized carrier concentrations of the u-InGaN/p-GaN and p-InGaN/p-GaN NWs were in the range of 1 × 10 16 and 7.6 × 10 15 cm -3 , respectively, while that of n-InGaN/n-GaN NWs exhibited the highest concentration of 5.7 × 10 17 cm -3 . As III-nitride NWs are naturally ntype, p-type dopants must usually go through a compensation step before the NWs exhibit ptype characteristics [17,18,20]. The Mg doping may induce more structural defects, which can behave as recombination centers and decrease the ionized dopant concentration [17,20].…”

Section: Methodsmentioning

confidence: 99%

“…Magnesium is a typical p-type dopant for III-nitride materials [16][17][18][19]. It has advantages including low formation energy and efficient dopant incorporation into NWs [19][20][21], and Mg-doped InGaN-based NWs have already been applied to PEC devices [2,17,22]. The previous study has been done on investigating the influence of doping concentration on tuning the surface Fermi level.…”

Section: Introductionmentioning

confidence: 99%

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Improved solar hydrogen production by engineered doping of InGaN/GaN axial heterojunctions

et al. 2019

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InGaN-based nanowires (NWs) have been investigated as efficient photoelectrochemical (PEC) water splitting devices. In this work, the InGaN/GaN NWs were grown by molecular beam epitaxy (MBE) having InGaN segments on top of GaN seeds. Three axial heterojunction structures were constructed with different doping types and levels, namely n-InGaN/n-GaN NWs, undoped (u)-InGaN/p-GaN NWs, and p-InGaN/p-GaN NWs. With the carrier concentrations estimated by Mott-Schottky measurements, a PC1D simulation further confirmed the band structures of the three heterojunctions. The u-InGaN/p-GaN and p-InGaN/p-GaN NWs exhibited optimized stability in pH 0 electrolytes for over 10 h with a photocurrent density of about -4.0 and -9.4 mA/cm 2 , respectively. However, the hydrogen and oxygen evolution rates of the Pt-treated u-InGaN/p-GaN NWs exhibited a less favorable stoichiometric ratio. On the other hand, the Pt-decorated p-InGaN/p-GaN NWs showed the best PEC performance, generating approximately 1000 µmol/cm 2 hydrogen and 550 µmol/cm 2 oxygen in 10 h. The band-engineered p-InGaN/p-GaN axial NWsheterojunction demonstrated a great potential for highly efficient and durable photocathodes.

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Quantified hole concentration in AlGaN nanowires for high-performance ultraviolet emitters

Cited by 24 publications

References 74 publications

Mapping the structural, electrical, and optical properties of hydrothermally grown phosphorus-doped ZnO nanorods for optoelectronic device applications

Mapping the structural, electrical, and optical properties of hydrothermally grown phosphorus-doped ZnO nanorods for optoelectronic device applications

Enhanced electro-optic performance of surface-treated nanowires: origin and mechanism of nanoscale current injection for reliable ultraviolet light-emitting diodes

Improved solar hydrogen production by engineered doping of InGaN/GaN axial heterojunctions

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