Study of Cs adsorption on (100) surface of [001]-oriented GaN nanowires: A first principle research

Xia, Sihao; Liu, Lei; Kong, Yike; Wang, Honggang; Wang, Meishan

doi:10.1016/j.apsusc.2016.07.050

Cited by 49 publications

(10 citation statements)

References 21 publications

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“…[31][32][33] Although the PBE method does not consider the excited state and thus underestimates the band gap value, the calculation can still predict the trend of electronic properties of GaN monolayer before and after Cs adsorption. 8,24 In addition, the Broyden-Flecher-Goldfarb-Shanno (BFGS) algorithm under GGA-PBE functional is used to optimize structure. 8,10,25 To obtain an accurate GaN monolayer model, we use the wurtzite GaN model to intercept an atomic layer along the (0001) plane as a unit cell and then establish a 4 × 4 × 1 supercell with 32 atoms, where the lattice constant is a = b = 3.189 Å.…”

Section: Models and Methodsmentioning

confidence: 99%

“…8,24 In addition, the Broyden-Flecher-Goldfarb-Shanno (BFGS) algorithm under GGA-PBE functional is used to optimize structure. 8,10,25 To obtain an accurate GaN monolayer model, we use the wurtzite GaN model to intercept an atomic layer along the (0001) plane as a unit cell and then establish a 4 × 4 × 1 supercell with 32 atoms, where the lattice constant is a = b = 3.189 Å. 31 The modeling of the GaN double-layer whose supercell size is also 4 × 4 × 1 comes from previous studies.…”

Section: Models and Methodsmentioning

confidence: 99%

“…Du et al 7 discussed the adsorption mechanism of Cs based on first principles and showed that Cs adsorption can reduce work function which is consistent with the experimental results. Xia et al 8 investigated optimal site and coverage of Cs adsorption on the surface of GaN nanowires, which showed that Cs adsorption can also reduce work function of GaN nanowires. These studies made a significant contribution to the exploration of GaN‐based optoelectronic devices.…”

Section: Introductionmentioning

confidence: 99%

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Structural and electronic properties of Cs‐adsorbed GaN monolayer and bilayer based on first principles

Liu

2021

Int J Energy Res

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A negative electron affinity photocathode can be obtained by adsorbing Cs on the emission layer surface of photocathode, which greatly improves the number of electrons escaped and the quantum efficiency. Based on first principles, this paper studies the structural and electronic properties of Cs-adsorbed GaN monolayer and bilayer. The results reveal that the Cs-adsorbed GaN monolayer is the most stable when Cs atom is adsorbed at T Ga site. There is a significant charge transfer between Cs atom and GaN monolayer, and the difference in electronegativity makes electrons of Cs atom transfer to GaN monolayer system. Cs adsorption can reduce band gap, work function, and electron affinity, which is conducive to the escape of electrons and improvement of quantum efficiency. Cs adsorption is helpful for tuning optical properties of GaN monolayer. For the GaN bilayer, greater stability and lower work function make the Cs adsorbed above the top layer of GaN bilayer be more beneficial to the improvement of photoelectric performance. Novelty StatementBased on first principles, this paper studies the structure and electric properties of Cs-adsorbed GaN monolayer and bilayer. Cs adsorption can reduce band gap, work function, and electron affinity, which is conducive to the escape of electrons and improvement of quantum efficiency. And for the GaN bilayer, greater stability and lower work function make the Cs adsorbed above the top layer of GaN bilayer be more beneficial to the improvement of photoelectric performance. K E Y W O R D Scharge transfer, Cs adsorption, first principles, GaN bilayer, GaN monolayer | INTRODUCTIONCs-activated GaN photocathode has been applied in flame detection, 1 corona detection, 2 ultraviolet communication, 3 and other fields. Because Cs activation plays an important role in reducing surface barrier and work function, it helps the photocathode achieve a negative electron affinity state which is beneficial to photoelectron emission. 4 In recent years, there are many theoretical and experimental studies on Cs-absorbed GaN surface reported successively. The GaN photocathode prepared by Machuca et al. 5 had a quantum efficiency (QE) of 50% at 310 nm after Cs activation. Norton et al 6 achieved a high-quality GaN emission layer with 40% QE at 185 nm by using Cs treatment. Du et al 7 discussed the adsorption mechanism of Cs based on first principles and showed that Cs adsorption can reduce

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Section: Models and Methodsmentioning

confidence: 99%

Section: Models and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural and electronic properties of Cs‐adsorbed GaN monolayer and bilayer based on first principles

Liu

2021

Int J Energy Res

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“…As is known, the adsorption energy per iron atom is calculated by the following formula [ 34 ]:

where E a is the adsorption energy, E tot is the total energy of the surface system after iron adsorption, E slab is the energy of the clean ZnO (0001) surface, and

is the chemical potential of a single iron atom.…”

Section: Calculation Models and Methodsmentioning

confidence: 99%

The Impact of Iron Adsorption on the Electronic and Photocatalytic Properties of the Zinc Oxide (0001) Surface: A First-Principles Study

et al. 2018

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The structural stability, electronic structure, and optical properties of an iron-adsorbed ZnO (0001) surface with three high-symmetry adsorption sites are investigated with first-principle calculations on the basis of density functional theory and the Hubbard-U method. It is found that the iron adatom in the H3 adsorption site of ZnO (0001) surface has the lowest adsorption energy of −5.665 eV compared with T4 and Top sites. For the Top site, compared with the pristine ZnO (0001) surface, the absorption peak located at 1.17 eV has a red shift, and the elevation of the absorption coefficient is more pronounced in the visible-light region, because the Fe-related levels are introduced in the forbidden band and near the Fermi level. The electrostatic potential computation reveals that the work function of the ZnO (0001) surface is significantly decreased from 2.340 to 1.768 eV when iron is adsorbed on the Top site. Furthermore, the degradation mechanism based on the band structure is analyzed. It can be concluded that the adsorption of iron will promote the separation of photoinduced carriers, thus improving the photocatalytic activity of ZnO (0001) surface. Our study benefits research on the photocatalytic activity of ZnO and the utilization rate of solar energy.

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“…Furthermore, we hope to find a positive effect of the optical absorption coefficient of the graded compositional Al x Ga 1−x N photocathode. Secondly, we have used the first‐principles principle to analyze the electronic and optical properties of nanostructured photocathodes . However, based on the limitations of research methods and technical equipment, we cannot continue to study the optical absorption of graded compositional Al x Ga 1−x N nanostructured photocathodes.…”

Section: Introductionmentioning

confidence: 99%

The effective light‐harvesting performance of graded compositional Al _x Ga _1−x N nano‐cone arrays photocathode for ultraviolet detector—A numerical investigation and simulation

Liu

Zhangyang

et al. 2020

Int J Energy Res

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A graded compositional Al x Ga 1−x N nanomaterial with a built-in electric field has been proposed to improve the quantum efficiency of the negative electronic affinity photocathode. When the graded compositional Al x Ga 1−x N nano-cone array is applied to the ultraviolet (UV) detector, it is necessary to improve the effective light absorption, which is high absorption in the UV short-wavelength and high sensitivity in the threshold wavelength. Therefore, the light absorption of nano-cone arrays with different feature sizes and geometrical properties is accurately calculated innovatively based on the finite-difference time-domain method. Studies show that a non-close-packed six-sided pyramid structure with a fill factor of 42.44% and a height of 1000 nm has an absorption spectrum that better satisfies the response characteristics of the UV detector. Surface reflection depends to a large extent on the transformation of the angle of incidence. The optical absorption properties of the graded compositional Al x Ga 1−x N nano-cone array provide flexibility and reference value for the improvement of the absorption coefficient and other parameters in the actual quantum efficiency experiment of the UV photocathode with built-in electric field, which can realize the highest sensitivity of various designed UV detector optical system.

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Study of Cs adsorption on (100) surface of [001]-oriented GaN nanowires: A first principle research

Cited by 49 publications

References 21 publications

Structural and electronic properties of Cs‐adsorbed GaN monolayer and bilayer based on first principles

Structural and electronic properties of Cs‐adsorbed GaN monolayer and bilayer based on first principles

The Impact of Iron Adsorption on the Electronic and Photocatalytic Properties of the Zinc Oxide (0001) Surface: A First-Principles Study

The effective light‐harvesting performance of graded compositional Al _x Ga _1−x N nano‐cone arrays photocathode for ultraviolet detector—A numerical investigation and simulation

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Study of Cs adsorption on (100) surface of [001]-oriented GaN nanowires: A first principle research

Cited by 49 publications

References 21 publications

Structural and electronic properties of Cs‐adsorbed GaN monolayer and bilayer based on first principles

Structural and electronic properties of Cs‐adsorbed GaN monolayer and bilayer based on first principles

The Impact of Iron Adsorption on the Electronic and Photocatalytic Properties of the Zinc Oxide (0001) Surface: A First-Principles Study

The effective light‐harvesting performance of graded compositional Al x Ga 1−x N nano‐cone arrays photocathode for ultraviolet detector—A numerical investigation and simulation

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The effective light‐harvesting performance of graded compositional Al _x Ga _1−x N nano‐cone arrays photocathode for ultraviolet detector—A numerical investigation and simulation