Charge Separation in Wurtzite/Zinc‐Blende Heterojunction GaN Nanowires

Wang, Zhiguo; Li, Jingbo; Gao, Fei; Weber, William J.

doi:10.1002/cphc.201000244

Cited by 6 publications

(7 citation statements)

References 37 publications

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“…Therefore, these structures clearly indicate the construction of a type I heterojunction [34][35][36] in which quantum confinement can be achieved, offering an effective way to obtain GeNR-based quantum well devices. The corresponding schematic description of this type I heterojunction is shown in Fig.…”

Section: Resultsmentioning

confidence: 85%

Modulating the band gap of germanane nanoribbons for quantum well devices

Zhou

Wang

et al. 2014

Phys. Chem. Chem. Phys.

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The effective modulation of the band gaps in nanostructures is of both fundamental and technological interest because a tunable band gap gives great flexibility in the design and optimization of nanodevices. Using density functional theory calculations, we have shown that germanane nanoribbons of various widths or under various strains can provide rich band gaps. Width- and strain-induced changes in the band gaps of germanane nanoribbons result from a reduction in quantum confinement with width and the weakening of sp(3) hybridization with strain, respectively. Both changes represent a monotonous relationship. To utilize such a monotonous change in band gap, we designed a quantum well based on germanane nanoribbons in which photoexcited electrons and holes occupy the same spatial region, resulting in a desirable light-emitting device.

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Section: Resultsmentioning

confidence: 85%

Modulating the band gap of germanane nanoribbons for quantum well devices

Zhou

Wang

et al. 2014

Phys. Chem. Chem. Phys.

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“…Moreover, it is believed that the large distribution and atomic level interconnection of twin-induced heterophase junctions in Cd 1−x Zn x S NCs lead to the vectorial interfacial transfer of photoexcited charge carriers between the ZB and WZ phase. 49,51 L-Cysteine molecules can bind to Cd 1−x Zn x S surfaces by coordination through the sulfur atoms and metal cations, as confirmed by IR analysis (Figure S6). The L-Cysteine ligand protects nanocrystals from oxidation and traps holes from NCs at the interface.…”

Section: Resultsmentioning

confidence: 74%

“…Furthermore, it was reported that the WZ phase occupies a CB and VB position higher than that of its ZB counterpart; consequently, the photoinduced electrons transfer from the CB of WZ to the CB of ZB, while holes migrate from the VB of ZB to the VB of WZ, achieving highly effective separation of electron–hole pairs. Moreover, it is believed that the large distribution and atomic level interconnection of twin-induced heterophase junctions in Cd 1– x Zn x S NCs lead to the vectorial interfacial transfer of photoexcited charge carriers between the ZB and WZ phase. , l -Cysteine molecules can bind to Cd 1– x Zn x S surfaces by coordination through the sulfur atoms and metal cations, as confirmed by IR analysis (Figure S6). The l -Cysteine ligand protects nanocrystals from oxidation and traps holes from NCs at the interface.…”

Section: Resultsmentioning

confidence: 85%

Bare Cd_1–xZn_xS ZB/WZ Heterophase Nanojunctions for Visible Light Photocatalytic Hydrogen Production with High Efficiency

Liang

Yuan

et al. 2016

ACS Appl. Mater. Interfaces

105

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In this work, we report the synthesis of Cd1-xZnxS zinc blende/wurtzite (ZB/WZ) heterophase nanojunctions with highly efficient charge separation by a solvothermal method in a mixed solution of diethylenetriamine (DETA) and distilled water. l-Cysteine was selected as a sulfur source and a protecting ligand for stabilization of the ZB/WZ homojunction. The optimal ternary chalcogenide Cd0.7Zn0.3S elongated nanocrystals (NCs) without any cocatalyst loading show very high visible light photocatalytic activity with H2 production efficiency of 3.13 mmol h(-1) and an apparent quantum efficiency of 65.7% at 420 nm. This is one of the best visible light photocatalysts ever reported for photocatalytic hydrogen production without any cocatalysts. The charge separation efficiency, having a critical role in enhancing photocatalytic activity for hydrogen production, was significantly improved. Highly efficient charge separation with a prolonged carrier lifetime is driven by the internal electrostatic field originating from the type-II staggered band alignment at the ZB/WZ junctions, as confirmed by steady and time-resolved photoluminescence spectra. Further, the strong binding between the l-cysteine ligand and Cd1-xZnxS elongated nanocrystals protects and stabilizes NCs; the l-cysteine ligand at the interface could trap holes from Cd1-xZnxS NCs, while photogenerated electrons transfer to Cd1-xZnxS catalytic sites for proton reduction. Our results demonstrate that Cd1-xZnxS ZB/WZ heterophase junctions stabilized by l-cysteine molecules can effectively separate charge carriers and achieve highly visible light photocatalytic hydrogen production. The present study provides a new insight into the design and fabrication of advanced materials with homojunction structures for photocatalytic applications and optoelectronic devices.

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“…Surprisingly, the AlN/GaN superlattice nanowire has the lowest work function, which may be due to a tiny internal field generated in sublayers. This internal field are also found form some heterojunction and superlattice structures 27,28 . The larger the composition difference between the sublayers, the higher the field intensity, and electrons inside nanowire are more easily migrated to the surface to escape, so the probability of the escape of the internal photoelectrons is increased, that is, the work function is reduced.…”

Section: Resultsmentioning

confidence: 87%

“…Therefore, Figure 4 shows structures. 27,28 The larger the composition difference between the sublayers, the higher the field intensity, and electrons inside nanowire are more easily migrated to the surface to escape, so the probability of the escape of the internal photoelectrons is increased, that is, the work function is reduced. The above results indicate that the field intensity is effectively controlled by changing composition of the superlattice nanowires to improve the emission performance of the photocathode.…”

Section: Electronic Properties Of Superlattice Nanowiresmentioning

confidence: 99%

Electronic properties of graded Ga _1‐x Al _x N superlattice nanowires photocathode: First‐principles

Liu

2020

Int J Energy Res

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Consider that a variable composition structure can introduce an internal field, stability, and photoelectric features of Ga 1-x Al x N superlattice nanowires having adjustable composition are studied. Different Al composition intervals and ratios in GaN nanowires are considered to create various superlattice nanowires. Structure and photoelectronic features of Ga 1-x Al x N superlattice nanowires having diameters of 7.4, 9.8, and 12.8 Å are investigated based on first principles. Increasing the content of Al atoms in the corresponding sublayers can reduce the formation energy, and can appear blue shifts in optical properties such as absorption coefficient. The continuously gradual built-in electric field makes Ga 1-x Al x N superlattice nanowires have a lower work function. The lowest work function can reach 4.27 eV, and the corresponding band gap is 3.812 eV. The direct band gap of Ga 1-x Al x N superlattice nanowires is influenced by the nanowire diameter, length, and sublayer. These studies can provide early guidance for improving the performance of spin-polarized electron sources. K E Y W O R D S electronic properties, first-principles, Ga 1-x Al x N, optical properties, superlattice nanowires Novelty Statement In this article, the structure stability, optoelectronic properties of Ga 1-x Al x N superlattice nanowires photocathodes is investigated through first-principles calculation for the application in the high-energy spin electron sources. The band structure of Ga 0.

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Charge Separation in Wurtzite/Zinc‐Blende Heterojunction GaN Nanowires

Cited by 6 publications

References 37 publications

Modulating the band gap of germanane nanoribbons for quantum well devices

Modulating the band gap of germanane nanoribbons for quantum well devices

Bare Cd_1–xZn_xS ZB/WZ Heterophase Nanojunctions for Visible Light Photocatalytic Hydrogen Production with High Efficiency

Electronic properties of graded Ga _1‐x Al _x N superlattice nanowires photocathode: First‐principles

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Charge Separation in Wurtzite/Zinc‐Blende Heterojunction GaN Nanowires

Cited by 6 publications

References 37 publications

Modulating the band gap of germanane nanoribbons for quantum well devices

Modulating the band gap of germanane nanoribbons for quantum well devices

Bare Cd1–xZnxS ZB/WZ Heterophase Nanojunctions for Visible Light Photocatalytic Hydrogen Production with High Efficiency

Electronic properties of graded Ga 1‐x Al x N superlattice nanowires photocathode: First‐principles

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Product

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Bare Cd_1–xZn_xS ZB/WZ Heterophase Nanojunctions for Visible Light Photocatalytic Hydrogen Production with High Efficiency

Electronic properties of graded Ga _1‐x Al _x N superlattice nanowires photocathode: First‐principles