Effect of crystal quality on performance of spin-polarized photocathode

Jin, Xiuguang; Ozdol, Burak; Yamamoto, Masahiro; Mano, Atsushi; Yamamoto, Naoto; Takeda, Yoshikazu

doi:10.1063/1.4902337

Cited by 35 publications

(16 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, these photocathodes have several important applications, including night vision image intensifiers, photo-multiplier tubes, polarized electron sources for next-generation electron accelerators, and electron beam lithography [1][2][3][4][5]. The quantum efficiency, electron spin polarization, stability, and reflectivity of GaAs film photocathodes have been widely investigated [6][7][8][9][10]. In the GaAs film photocathodes, the photoelectrons can only be emitted when they have been transported to the cathode surface.…”

Section: Introductionmentioning

confidence: 99%

Theoretical analysis and modeling of photoemission characteristics of GaAs nanowire array photocathodes

Zou

Deng

et al. 2015

Mater. Res. Express

View full text Add to dashboard Cite

Gallium arsenide (GaAs) nanowire array (NWA) photocathodes have unique electrical and optical properties. Based on studies about photon absorption, band structure, and electron transport properties of GaAs nanowire, a photoemission model for GaAs NWA photocathodes is established. According to the model, we simulate and analyze the photocurrent, spectral response, and absorption properties of ordered GaAs NWA photocathodes. The results present a very interesting phenomenon; the photocurrent and spectral response peak at incident angles of 20°and 30°, respectively. These special properties of NWA cathodes differentiate them from their thin film counterparts. We also analyze the effects of nanowire length and diameter on the photocurrent of NWA cathodes, and find the optimum height of the nanowires is 10 μm. This study shows that NWAs exhibit higher absorbance and excellent charge transport. Thus, GaAs NWA photocathodes are excellent candidates for electron sources.

show abstract

Section: Introductionmentioning

confidence: 99%

Theoretical analysis and modeling of photoemission characteristics of GaAs nanowire array photocathodes

Zou

Deng

et al. 2015

Mater. Res. Express

View full text Add to dashboard Cite

show abstract

“…Thus, drift and other scanning distortions do not affect the strain measurements. The sample studied here was extracted from a high-efficiency photocathode device, 19 which consists of GaAs/GaAsP super-lattice (SL) grown on a AlGaAsP virtual substrate that was grown on (001) GaP substrate. Crosssectional wedge TEM specimens were prepared by automated mechanical polishing (Allied MultiPrep) followed by low energy Argon ion milling in a cooled stage (Gatan PIPS 2) (200 eV, À150 C ) to minimize the ion beam-induced surface damage.…”

mentioning

confidence: 99%

Strain mapping at nanometer resolution using advanced nano-beam electron diffraction

Özdöl

Gammer

Jin

et al. 2015

Applied Physics Letters

185

123

View full text Add to dashboard Cite

We report on the development of a nanometer scale strain mapping technique by means of scanning nano-beam electron diffraction. Only recently possible due to fast acquisition with a direct electron detector, this technique allows for strain mapping with a high precision of 0.1% at a lateral resolution of 1 nm for a large field of view reaching up to 1 μm. We demonstrate its application to a technologically relevant strain-engineered GaAs/GaAsP hetero-structure and show that the method can even be applied to highly defected regions with substantial changes in local crystal orientation. Strain maps derived from atomically resolved scanning transmission electron microscopy images were used to validate the accuracy, precision and resolution of this versatile technique.

show abstract

“…Recently, with the rapid development of space detection, high-resolution night-vision imaging, next-generation electron accelerators, lowenergy electron microscopes, and electron beam lithography, an ever-pressing demand has arisen for photocathodes with higher sensitivity, wider spectral response range, higher emission current density, and higher spin polarization. Thus, some new GaAs-based photoemission material structures, such as graded doping/band-gap [6][7][8], strained [9], and superlattice structures [10][11][12], have been proposed to increase the quantum efficiency or spin polarization of GaAs-based photocathodes. However, all of these new photoemission materials rely on GaAs-based epitaxial thin films as the active layers of photocathodes.…”

Section: Introductionmentioning

confidence: 99%

Negative electron affinity GaAs wire-array photocathodes

Zou

Zhang

et al. 2016

Opt. Express

View full text Add to dashboard Cite

Negative electron affinity GaAs wire-array photocathodes have been fabricated by reactive ion etching and inductively coupled plasma etching of bulk GaAs material followed by Cs-O activation. Scanning electron microscope has revealed that the thus obtained high-density GaAs wire arrays had high periodicity, large height, and good morphology. Photoluminescence spectra indicated the wire arrays were of good crystalline quality and free from any obvious damage. Compared to the original GaAs wafer, the photoluminescence peak positions of the wire arrays were somewhat red-shifted, which may be attributed to the temperature effect and strain relaxation. The wire-array structures showed significantly reduced light reflection compared with the original wafer due to the excellent light-trapping effect. Cs-O activation experiments of the GaAs wire arrays have been performed to reveal the effect of incident angle on quantum efficiency. The results show that maximum quantum efficiency was obtained at about 30°. Given these unique electrical and optical properties, a GaAs wire-array photocathode is an attractive alternative to its planar-structured counterpart.

show abstract

Effect of crystal quality on performance of spin-polarized photocathode

Cited by 35 publications

References 16 publications

Theoretical analysis and modeling of photoemission characteristics of GaAs nanowire array photocathodes

Theoretical analysis and modeling of photoemission characteristics of GaAs nanowire array photocathodes

Strain mapping at nanometer resolution using advanced nano-beam electron diffraction

Negative electron affinity GaAs wire-array photocathodes

Contact Info

Product

Resources

About