Electron emission from GaAs(Cs,O): Transition from negative to positive effective affinity

Журавлев, А. Г.; Khoroshilov, V S; Alperovich, V. L.

doi:10.1016/j.apsusc.2019.04.010

Cited by 22 publications

(13 citation statements)

References 36 publications

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“…The experimental procedure of Cs activation was as follows: The Cs source was turned on, the photocurrent curve started to rise slowly, and after the activation photocurrent reached the first peak, the Cs source was turned off to stop the activation, and the sample was analyzed by surface XPS and UPS immediately. After that, Cs/O alternating activation was performed [11,12] , and surface XPS and UPS analyses were carried out after the photocurrent peak continued to rise to the maximum value. The XPS spectral curves of C1s and O1s after different experimental steps are given in Fig.…”

Section: Activation Analysismentioning

confidence: 99%

Integrated ultrahigh vacuum facility for photocathode preparation and in-situ characterization

Zhang,

Qian,

Zhang

et al. 2023

Functional Material Applications: From Energy to Sensing

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As the photoelectric conversion material, semiconductor photocathode plays an important role in the development of vacuum photodetectors and electron sources, and the efficiency and stability of electron emission have always been the focus in photocathode applications. Photocathode is based on the external photoelectric effect. Different from the internal photoelectric effect, photoelectrons generated by light excitation inside the cathode must overcome the surface barrier to escape into the vacuum, so the level of the photoemission ability is closely related to the surface properties. The preparation process usually includes surface cleaning and activation, wherein the activation process under the ultrahigh vacuum condition is regarded as an irreversible and evolutionary process over time. How to characterize the cathode surface in situ is particularly important for understanding the mechanism of photoemission generation and degradation. Nowadays, the surface characterization methods including photoelectron spectroscopy, synchrotron x-ray characterization, electron diffraction, scanning probe microscopy, spectral response measurement, and photoreflectance spectroscopy are utilized as assisted evaluation tools to prepare photocathodes. Here, we present a newly developed integrated ultrahigh vacuum facility for photocathode preparation and in-situ characterization. With this system, the surface cleaning, activation and degradation processes for semiconductor photocathodes were effectively characterized by photoelectron spectroscopy and spectral measurement. The integrated photocathode preparation and characterization system can realize in-situ multi-information characterization in ultra-high vacuum environment, and the element composition and chemical state analysis of the specified region can be realized by using X-ray secondary electron image and micro-area analysis function, which is helpful to optimize the preparation process of photocathodes.

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Section: Activation Analysismentioning

confidence: 99%

Integrated ultrahigh vacuum facility for photocathode preparation and in-situ characterization

Zhang,

Qian,

Zhang

et al. 2023

Functional Material Applications: From Energy to Sensing

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“…Интерес к поверхностям с небольшим положительным электронным сродством (ПЭС) χ * ≈ 0.2−0.4 eV связан с возможностью повышения эффективности преобразования солнечной энергии [2]. В работах [3,4] переход между состояниями поверхности p-GaAs(Cs,O) с ОЭС и ПЭС изучался методом спектроскопии квантового выхода фотоэмиссии (КВФЭ) при освещении со стороны эмитирующей поверхности (геометрия " на отражение"). В такой геометрии ранее наблюдался только монотонный рост КВФЭ при увеличении энергии фотонов, обусловленный увеличением коэффициента поглощения в области межзонных переходов [1].…”

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“…Нанесением цезия и кислорода поверхность активировалась до состояния с ОЭС. Затем на активированную поверхность наносился избыточный кислород или цезий, что приводило к переходу от ОЭС к ПЭС и деградации тока фотоэмиссии [3,4]. В процессе деградации измерялись спектры КВФЭ в геометрии на отражение.…”

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Пленение излучения и субзонный пик в спектрах квантового выхода фотоэмиссии из p-GaAs(Cs,O)

Хорошилов¹,

Протопопов²,

Казанцев³

et al. 2023

Письма В Журнал Технической Физики

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In the spectra of the photoemission quantum yield of p-GaAs(Cs,O) measured in the reflection geometry, a peak was found at a photon energy lower than the band gap of GaAs. It is shown that the appearance of the peak is due to the trapping of weakly absorbed radiation, which scatters diffusely on the rough back face of the epitaxial structure. Possible microscopic mechanisms of the appearance of the peak are discussed: the Franz-Keldysh effect in the surface electric field and adsorption-modified optical transitions in cesium adatoms.

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“…The interest in surfaces with small positive electron affinity (PEA) χ * ≈ 0.2−0.4 eV stems from the potential to raise the efficiency of solar energy conversion [2]. The transition between p-GaAs(Cs,O) surfaces with NEA and PEA was examined in [3,4] using the photoemission quantum yield (PEQY) spectroscopy technique under illumination from the side of the emitting surface ( " reflection"geometry). Only a monotonic PEQY growth with an increase in photon energy, which is attributable to an enhancement of the absorption coefficient in the region of interband transitions [1], has been observed earlier in this geometry.…”

mentioning

confidence: 99%

“…Excess oxygen or cesium were then deposited onto the activated surface. This induced a transition from NEA to PEA and suppressed the photoemission current [3,4]. PEQY spectra were measured in the refection geometry during photocurrent degradation.…”

mentioning

confidence: 99%

Light trapping and subbandgap maximum in photoemission quantum yield spectra of p-GaAs(Cs,O)

Khoroshilov

Protopopov

Kazantsev

et al. 2023

Technical Physics Letters

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Electron emission from GaAs(Cs,O): Transition from negative to positive effective affinity

Cited by 22 publications

References 36 publications

Integrated ultrahigh vacuum facility for photocathode preparation and in-situ characterization

Integrated ultrahigh vacuum facility for photocathode preparation and in-situ characterization

Пленение излучения и субзонный пик в спектрах квантового выхода фотоэмиссии из p-GaAs(Cs,O)

Light trapping and subbandgap maximum in photoemission quantum yield spectra of p-GaAs(Cs,O)

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