Study on depuration technics for negative electron affinity GaN photocathode

Qiao, Jian‐Tian; Chang, Benkang; Qian, Yunsheng; Li, B; Wang, X H; Gao, Peng

doi:10.1109/ivesc.2010.5644317

Cited by 2 publications

(4 citation statements)

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“…H atoms are passivated on other five sides to reduce surface state [23], as shown in figure 1(b). The valence electron configurations of N, Ga, Al, Cs, O and H are 2s 2 2p 3 , 3d 10 4s 2 4p 1 , 3s 2 3p 1 , 5s 2 5p 6 , 2s 2 2p 4 and 1s 1 , respectively. Finally, we have used the DFT-D3 of Tkatchenko and Scheffler method to calculate the energy of activated Al 0.5 Ga 0.5 N surface models.…”

Section: Calculation and Model Detailsmentioning

confidence: 99%

“…Negative electron affinity (NEA) GaN photocathode has be a worthwhile component of optoelectronic devices such as UV detectors due to their low dark emission, wide bandwidth gap and excellent quantum efficiency [1,2]. Although the NEA The light emission performance and quantum efficiency of photocathode are greatly promoted with the improvement of p-type doping technology, surface cleaning technology and surface activation technology [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Exploration on structural stability, electronic and optical properties of Cs-activated and Cs/O-activated Al_0.5Ga_0.5N thin film and nanowire photocathode surface

Tian,

Liu,

et al. 2023

J. Phys.: Condens. Matter

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To explore effects of surface activation on AlGaN-based photocathode, this paper analyzes in detail the structural stability, charge transfer, band structure, density of states, absorption coefficient and reflectivity of Cs-activated and Cs/O-activated Al0.5Ga0.5N thin films and nanowires by using first-principles. Our results reveal that adsorption energy of Al0.5Ga0.5N thin films and nanowires adsorbed by Cs will gradually increase as Cs coverage increases, and structural stability will be weakened. Cs-adsorbed thin film surfaces are more stable than nanowire when Cs coverage is same. Cs/O co-adsorbed Al0.5Ga0.5N systems are more stable under high Cs coverage. And Cs/O co-adsorbed Al0.5Ga0.5N possess the most stable structure when the ratio of Cs to O is 2:1. Band structure and density of states imply that Cs and O adsorption introduce new energy levels, which are derived from s, p orbitals of Cs and s orbitals of O, respectively. Furthermore, only when the Cs/O ratio is 2:1, the work function of Al0.5Ga0.5N thin film is lower than that of Cs-only adsorption, which is conducive to electron escape and improving quantum efficiency. Results of optical properties show that Cs activation and Cs/O activation can greatly improve the optical performance of Al0.5Ga0.5N.

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Section: Calculation and Model Detailsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Exploration on structural stability, electronic and optical properties of Cs-activated and Cs/O-activated Al_0.5Ga_0.5N thin film and nanowire photocathode surface

Tian,

Liu,

et al. 2023

J. Phys.: Condens. Matter

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“…[1][2][3] Group III nitrides represented by GaN have advantages of high breakdown voltage, wide band gap and high quantum efficiency. 4,5 They are materials of choice for developing photocathodes in ultraviolet detectors. With the improvement of solid physics and semiconductor physics theories, it is found that band gap of AlGaN has been continuously increased from 3.42 to 6.2 eV by adjusting Al contents in AlGaN crystal material.…”

Section: Introductionmentioning

confidence: 99%

“…Ultraviolet detection is a novel technique developed after infrared detection and laser detection, and is used in many fields such as ultraviolet communication, marine oil pollution detection, and space detection 1‐3 . Group III nitrides represented by GaN have advantages of high breakdown voltage, wide band gap and high quantum efficiency 4,5 . They are materials of choice for developing photocathodes in ultraviolet detectors.…”

Section: Introductionmentioning

confidence: 99%

Theoretical exploration of quantum efficiency ofAl_xGa_1 −xNmonolayer photocathode with varying Al contents and ultra‐thin emission layer

Liu

2020

Int J Energy Res

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To obtain high-efficiency AlGaN monolayer photocathode, the quantum efficiency formulas of reflection-mode and transmission-mode Al x Ga 1 − x N monolayer photocathode with varying Al contents and ultra-thin emission layer are derived in this article. Based on the formulas, we have simulated quantum efficiency of Al x Ga 1 − x N monolayer photocathode under different conditions. The results reveal that built-in electric field caused by varying Al contents can significantly promote quantum efficiency of photocathode. If difference in Al contents between adjacent Al x Ga 1 − x N monolayer enlarges, quantum efficiency will decrease. At the same time, built-in electric field also plays a great impact in stabilizing quantum efficiency and photoelectric emission performance of Al x Ga 1 − x N monolayer photocathode. The ideal quantum efficiency and photoelectric emission performance can be obtained when buffer layer thickness is about 50 to 75 nm. In addition, when emission layer is composed of a larger number of Al x Ga 1 − x N monolayers with varying Al contents, the more number of monolayers with high Al contents are, the higher the quantum efficiency is. This study can give useful help for design and preparation of Al x Ga 1 − x N monolayer photocathodes with varying Al contents.

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Study on depuration technics for negative electron affinity GaN photocathode

Cited by 2 publications

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Exploration on structural stability, electronic and optical properties of Cs-activated and Cs/O-activated Al_0.5Ga_0.5N thin film and nanowire photocathode surface

Exploration on structural stability, electronic and optical properties of Cs-activated and Cs/O-activated Al_0.5Ga_0.5N thin film and nanowire photocathode surface

Theoretical exploration of quantum efficiency ofAl_xGa_1 −xNmonolayer photocathode with varying Al contents and ultra‐thin emission layer

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Study on depuration technics for negative electron affinity GaN photocathode

Cited by 2 publications

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Exploration on structural stability, electronic and optical properties of Cs-activated and Cs/O-activated Al0.5Ga0.5N thin film and nanowire photocathode surface

Exploration on structural stability, electronic and optical properties of Cs-activated and Cs/O-activated Al0.5Ga0.5N thin film and nanowire photocathode surface

Theoretical exploration of quantum efficiency ofAlxGa1 −xNmonolayer photocathode with varying Al contents and ultra‐thin emission layer

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Exploration on structural stability, electronic and optical properties of Cs-activated and Cs/O-activated Al_0.5Ga_0.5N thin film and nanowire photocathode surface

Exploration on structural stability, electronic and optical properties of Cs-activated and Cs/O-activated Al_0.5Ga_0.5N thin film and nanowire photocathode surface

Theoretical exploration of quantum efficiency ofAl_xGa_1 −xNmonolayer photocathode with varying Al contents and ultra‐thin emission layer