Highly spin-polarized electron photocathode based on GaAs–GaAsP superlattice grown on mosaic-structured buffer layer

Jin, Xiuguang; Maeda, Yoshiyuki; Saka, Takashi; Tanioku, Masatoshi; Fuchi, Shingo; Ujihara, Toru; Takeda, Yoshikazu; Yamamoto, Naoto; Nakagawa, Yuki; Mano, Atsushi; Okumi, Shoji; Yamamoto, Masahiro; Nakanishi, Toru; Horinaka, Hiromichi; Kato, Toshihiro; Yasue, Tsuneo; Koshikawa, Takanori

doi:10.1016/j.jcrysgro.2008.07.001

Cited by 24 publications

(16 citation statements)

References 19 publications

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“…To realize this system, a GaAs/GaAsP strained superlattice was fabricated on a GaP substrate (bandgap energy: 2.26 eV), which is transparent to the pump-laser beam (beam energy: 1.441.77 eV), instead of a GaAs (bandgap energy: 1.42 eV) substrate. High spin-polarization (90%) and a super-high brightness (1.310 7 Acm  sr  ) electron beam were reproducibly achieved with this transmission-type photocathode. The key technology to achieve the high spin-polarization in this photocathode is the introduction of a 500 nm GaAs inter-layer deposited on the GaP substrate.…”

Section: Introductionmentioning

confidence: 79%

“…In the GaAsP layer on the GaAs substrate, some cracks along [110] and [1][2][3][4][5][6][7][8][9][10] directions were observed as shown in Figure 3 (a). Except the cracks areas, the surface of GaAsP layer shows relatively flat.…”

Section: Surface Morphology Of Gaasp Buffer Layer On Various Substratesmentioning

confidence: 99%

“…Photocathodes based on a GaAs/GaAsP strained superlattice [4,5] and an AlInGaAs/AlGaAs strained superlattice [6] provide high spin-polarizations over 90%. In our previous study [5,7] we have newly developed a super-high-brightness transmission-type photocathode based on the GaAs/GaAsP strained superlattice. In this novel system, a super-high brightness electron beam was achieved by illuminating a small area on the backside of the photocathode with a pump laser light that was well-focused by a short-focal-length lens.…”

Section: Introductionmentioning

confidence: 99%

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Elimination of local thickness modulation in GaAs/GaAsP strained superlattices for high spin-polarization photocathodes

Jin¹,

Maeda²,

Sasaki³

et al. 2011

J. Phys.: Conf. Ser.

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Section: Introductionmentioning

confidence: 79%

Section: Surface Morphology Of Gaasp Buffer Layer On Various Substratesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Elimination of local thickness modulation in GaAs/GaAsP strained superlattices for high spin-polarization photocathodes

Jin¹,

Maeda²,

Sasaki³

et al. 2011

J. Phys.: Conf. Ser.

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“…In addition to this reflection, about 60% of the pump laser light (hν: 1.59 eV) is absorbed by a 600-nm-thick GaAs inter-layer that was deposited on the GaP substrate. The GaAs inter-layer was necessary to obtain the periodic GaAs/GaAsP SL layers [15,16]. Therefore, about only 28% of the pump laser light reaches the 12 pairs of GaAs/GaAsP strained SL structure.…”

Section: Introductionmentioning

confidence: 99%

Improvement of Quantum Efficiency in Transmission-Type Spin-Polarized Photocathode

Jin¹,

Ichihashi²,

Mano³

et al. 2016

IJMSA

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Abstract:We successfully developed a new transmission-type GaAs/GaAsP strained superlattice photocathode with an AlGaAs transparent inter-layer and Si 3 N 4 anti-reflection coating. The electrons emitted from this photocathode showed a high spin polarization of 90% with a quantum efficiency as high as 0.4%. In the application for spin-polarized low energy electron microscope, a high emission current of over 1 µA was observed at 3.6 mW pump laser power. Transmission electron microscopy observation revealed that there were a small disorder and some dislocations in the GaAs/GaAsP superlattice layers. The disordered superlattice layers result in a fluctuation of the superlattice band structure and the dislocations trap the photo-electrons during the diffusion to the surface. Both of the defects influenced the performance of spin-polarized photocathode.

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“…Photocathode growth on GaAs substrates resulted in high polarization, with a maximum value as high as 92% [10]. In contrast, the maximum polarization was as low as 64% when using GaP substrates, for reasons discussed in another paper [11]. The polarization was improved by inserting a 500-nm-thick GaAs layer between the GaP substrate and GaAsP layer [12,13].…”

Section: Introductionmentioning

confidence: 99%

Strain of GaAs/GaAsP Superlattices Used as Spin-Polarized Electron Photocathodes, Determined by X-Ray Diffraction

Saka

Ishida

Kanda

et al. 2010

e-J. Surf. Sci. Nanotechnol.

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The strains in GaAs/GaAsP superlattices used in spin-polarized photocathodes grown on GaAs and GaP (001) substrates were determined by X-ray diffraction. The thicknesses of the GaAs wells and GaAsP barrier layers were also determined. The band structures of the superlattices were calculated on the basis of these experimentally determined strains and layer thicknesses. The thicknesses and band structures were in good agreement with those observed by transmission electron microscopy and photoluminescence, respectively. The strains induced in the GaAs well layers were approximately linearly dependent upon the phosphorous fraction in the GaAsP layer, and the splitting between the heavy hole band and the light hole band of the superlattices grown on GaP substrates was larger than that of superlattices grown on GaAs substrates. In photocathodes grown on GaP substrates, low polarizations were observed, not due to a lack of band splitting, but to depolarization scattering caused by crystal defects, which were different from that induced in superlattices grown on GaAs substrates.

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Highly spin-polarized electron photocathode based on GaAs–GaAsP superlattice grown on mosaic-structured buffer layer

Cited by 24 publications

References 19 publications

Elimination of local thickness modulation in GaAs/GaAsP strained superlattices for high spin-polarization photocathodes

Elimination of local thickness modulation in GaAs/GaAsP strained superlattices for high spin-polarization photocathodes

Improvement of Quantum Efficiency in Transmission-Type Spin-Polarized Photocathode

Strain of GaAs/GaAsP Superlattices Used as Spin-Polarized Electron Photocathodes, Determined by X-Ray Diffraction

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