Spectral transmittance and module structure fitting for transmission-mode GaAs photocathodes

赵静,; 常本康,; 熊雅娟,; 张益军,

doi:10.1088/1674-1056/20/4/047801

Cited by 15 publications

(2 citation statements)

References 21 publications

(11 reference statements)

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“…However, due to the large absorption coefficient of In 0.15 Ga 0.85 As in the NIR region, more photoelectrons can be excited to the conduction band, which is beneficial for the photoemission process of the In 0.15 Ga 0.85 As photocathode. Meanwhile, the FWHM of the In 0.15 Ga 0.85 As photocathode is 10.2 ps at a thickness of 1.6 μm, which is much lower than that of the traditional GaAs photocathode (~69 ps at a wavelength of 860 nm) [ 14 ] and InP/InGaAs (~35 ps at 1550 nm) [ 41 ], and can meet the ultrafast response requirements of imaging intensifiers and atomic lifetime detectors in the NIR region.…”

Section: Resultsmentioning

confidence: 99%

Theoretical Study on the Photoemission Performance of a Transmission Mode In0.15Ga0.85As Photocathode in the Near-Infrared Region

et al. 2023

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Benefiting from a high quantum efficiency, low thermal emittance, and large absorption coefficient, InxGa1−xAs is an excellent group III–V compound for negative electron affinity (NEA) photocathodes. As the emission layer, InxGa1−xAs, where x = 0.15, has the optimal performance for detection in the near-infrared (NIR) region. Herein, an NEA In0.15Ga0.85As photocathode with Al0.63Ga0.37As as the buffer layer is designed in the form of a transmission mode module. The electronic band structures and optical properties of In0.15Ga0.85As and Al0.63Ga0.37As are calculated based on density functional theory. The time response characteristics of the In0.15Ga0.85As photocathode have been fully investigated by changing the photoelectron diffusion coefficient, the interface recombination velocity, and the thickness of the emission layer. Our results demonstrate that the response time of the In0.15Ga0.85As photocathode can be reduced to 6.1 ps with an incident wavelength of 1064 nm. The quantum efficiency of the In0.15Ga0.85As photocathode is simulated by taking into account multilayer optical thin film theory. The results indicate that a high quantum efficiency can be obtained by parameter optimization of the emission layer. This paper provides significant theoretical support for the applications of semiconductor photocathodes in the near-infrared region, especially for the study of ultrafast responses in the photoemission process.

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Section: Resultsmentioning

confidence: 99%

Theoretical Study on the Photoemission Performance of a Transmission Mode In0.15Ga0.85As Photocathode in the Near-Infrared Region

et al. 2023

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“…Hence, a new fitting equation must be determined. The electron potential barrier between the GaAs active layer and the Al x Ga 1−x As buffer layer are calculated by [7] …”

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Research on surface photovoltage spectroscopy for GaAs photocathodes with AlxGa1?xAs buf fer layer

Zhang¹,

Chen²,

Zhuang³

2012

中国光学快报

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Surface photovoltage spectroscopy equations for cathode materials with an AlxGa1−xAs buffer layer are determined in order to effectively measure the body parameters for transmission-mode (t-mode) photocathode materials before Cs-O activation. Body parameters of cathode materials are well fitted through experiments and fitting calculations for the designed AlxGa1−xAs/GaAs structure material. This investigation examines photo-excited performance and measurements of body parameters for t-mode cathode materials of different doping structures. It also helps study various doping structures and optimize structure designs in the future.OCIS After Cs-O activation, the surface barriers of GaAs photocathodes can become negative electron affinity (NEA), driving photo-excited electrons to tunnel through surface barriers into a vacuum. Thus, NEA GaAs photocathodes have been widely used in night-vision image intensifiers, photomultiplier tubes, and polarized electron sources due to their excellent wavelength response, high quantum efficiency, and good spin polarization [1] . NEA photocathodes are of two types: a reflection-mode (r-mode) cathode, in which the incident light and electron emission surface are on the same side, and a transmission-mode (tmode) cathode, in which the incident light and electron emission surface are on different sides. In practical applications, NEA photocathodes often operate in t-mode, but the measurement techniques for t-mode cathode materials before activation are inadequate [2] . As the buffer layer matching the lattice between the Si 3 N 4 antireflective film and GaAs active layer, the Al x Ga 1−x As layer helps reflect the photo-excited electrons to the active layer and finally promotes quantum efficiency for NEA photocathodes. In previous studies, the measurements for GaAs photocathodes mainly depend on the spectral response curve (SRC) after activation. However, the parameters of GaAs photocathodes cannot be effectively measured by SRC alone, because the performances of cathodes after activation are influenced not only by material parameters mainly connected with the doping structure and epitaxial growth technique, but also by surface barriers mainly related to Cs-O activation techniques. Surface photovoltage spectroscopy (SPS) is connected only to the performance of cathode materials. Thus, in recent research, SPS has been widely used to measure material parameters, such as electron diffusion length and interface recombination velocity, for cathode materials with an r-mode structure. A comparative research between SPS before activation and SRC after activation has also exactly fitted the surface escape probability [3] . The SPS fitting theory is inadequate for the t-mode material, which has a more complex structure than the r-mode cathode. Thus, the SPS research for cathode materials with the Al x Ga 1−x As buffer layer can help in further building the SPS theory for t-mode photocathodes [4] . The main difference between the t-mode and r-mode

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Effect of multilayer complex buffer layer structures on photoelectric performance of GaAs-based photocathodes

et al. 2022

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Spectral transmittance and module structure fitting for transmission-mode GaAs photocathodes

Cited by 15 publications

References 21 publications

Theoretical Study on the Photoemission Performance of a Transmission Mode In0.15Ga0.85As Photocathode in the Near-Infrared Region

Theoretical Study on the Photoemission Performance of a Transmission Mode In0.15Ga0.85As Photocathode in the Near-Infrared Region

Research on surface photovoltage spectroscopy for GaAs photocathodes with AlxGa1?xAs buf fer layer

Effect of multilayer complex buffer layer structures on photoelectric performance of GaAs-based photocathodes

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