The photoemission characteristics of a NEA InGaN photocathode by simultaneously supplying Cs and O2

Kashima, Masahiro; Itokawa, Yuya; Kanai, Toshiya; Koizumi, Akira; Iijima, H.; Nishitani, T.; Honda, Yoshio; Amano, Hiroshi; Meguro, Takeshi

doi:10.1016/j.apsusc.2022.153882

Cited by 9 publications

(4 citation statements)

References 31 publications

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“…The absorption coefficient of the emission layer can be derived from Figure 4 a. The reflectivity of the photocathode (R) is calculated by using optical film matrix theory, which reports a consistent trend in InGaAs-based devices, and hence the reflectivity value is fixed at 0.3 as well [ 27 ]. In order to study the time response of the In 0.15 Ga 0.85 As photocathode in the NIR region, the incident light is selected as a Gauss pulse with a wavelength of 1064 nm, and all photoelectron densities emitted by the In 0.15 Ga 0.85 As photocathode were normalized to the incident signal.…”

Section: Resultsmentioning

confidence: 99%

“…Hence, we also analyzed the impact factors of the quantum efficiency, including D n , S v , and T e . Related to the properties of the material, the thickness of the buffer layer was set as 0.2 μm [ 23 ] and the electron diffusion length was 1.7 μm [ 27 ]. By fixing S v at 10 4 cm/s and T e at 1.8 um, the quantum efficiency curves of the proposed structure with different electron diffusion coefficients of In 0.15 Ga 0.85 As are simulated for optimal performance of the photocathode, as given in Figure 6 a.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, doping is a helpful step for the formation of the NEA photocathode, and can also be used to guide the In x Ga 1−x As material growth for the photocathode [ 26 ]. Moreover, the NEA activation procedure, in which cesium and oxygen adsorption are alternately supplied on the photocathode surface, can make the surface vacuum level of the NEA photocathodes lower than the conduction band minimum (CBM) of the bulk and result in a high QE [ 27 , 28 ]. Aside from the QE, the response time also plays a significant role in the photoemission process, and has attracted great interest in recent years.…”

Section: Introductionmentioning

confidence: 99%

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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%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…The possibility of multiple adsorption forms of Cs and O 2 has also been reported experimentally for InGaN, a nitride semiconductor. 33) The number of adsorbed components and the θ 0 increase on the Al 0.5 Ga 0.5 N surface codeposited with Cs/O 2 compared to Cs. The increase in thermionic emission current due to the alternating Cs/O 2 supply shown in Fig.…”

Section: Mrm Fitting Of Thermionic Emission Current Frommentioning

confidence: 98%

Surface activation of n-type AlGaN with cesium and oxygen to enhance thermionic emission

Namura,

Kimura,

Miyazaki

et al. 2024

Jpn. J. Appl. Phys.

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The paper describes the characteristics of thermionic emission of AlGaN surface through surface control employing cesium (Cs) and oxygen. The thermionic emission current of AlGaN surfaces with Cs and oxygen was measured, and the surface state of AlGaN was analyzed by employing a new material-independent thermionic emission model (MRM) based on the Richardson-Dushman equation successfully reproduced the thermionic emission behavior of Cs-deposited and Cs/O2 co-deposited AlGaN, considering the dynamic change of the surface layer caused by thermal desorption of Cs. These results indicate that AlGaN co-deposited with Cs/O2 could be applied as a thermionic energy converter operating in a lower to medium temperature range (200-800 °C), as compared to conventional devices.

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Enhancement of near-infrared response of InGaAs photocathode through interaction of 1064 nm light with activated surface

Wang

Zhang

et al. 2023

Applied Surface Science

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The photoemission characteristics of a NEA InGaN photocathode by simultaneously supplying Cs and O2

Cited by 9 publications

References 31 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

Surface activation of n-type AlGaN with cesium and oxygen to enhance thermionic emission

Enhancement of near-infrared response of InGaAs photocathode through interaction of 1064 nm light with activated surface

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