Brightness evaluation of pulsed electron gun using negative electron affinity photocathode developed for time-resolved measurement using scanning electron microscope

Morishita, Hideo; Ohshima, Takashi; Otsuga, K.; Kuwahara, Makoto; Agemura, Toshihide; Ose, Yoichi

doi:10.1016/j.ultramic.2021.113386

Cited by 9 publications

(2 citation statements)

References 15 publications

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“…After being reflected by an ultraviolet (UV)-enhanced aluminum mirror, it converged onto the thermionic LaB 6 cathode tip at an incident angle of 30 • , thereby generating primary photoelectrons. Different from the traditional side-illumination method for wire-like field emitters [29][30][31] or backside illumination for flat photocathodes [32][33][34], a planar LaB 6 cathode with a diameter of 100 µm, which is consistent with the size of the electrongenerating light spot, means that this bottom-up photoelectron generation scheme is appropriate. In continuous emission mode, the vacuum required for the LaB 6 cathode is generally much lower than that for field emitters.…”

Section: Instrumentsmentioning

confidence: 99%

Spatiotemporal Visualization of Photogenerated Carriers on an Avalanche Photodiode Surface Using Ultrafast Scanning Electron Microscopy

Tian,

Yang,

et al. 2024

Nanomaterials

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The spatiotemporal evolution of photogenerated charge carriers on surfaces and at interfaces of photoactive materials is an important issue for understanding fundamental physical processes in optoelectronic devices and advanced materials. Conventional optical probe-based microscopes that provide indirect information about the dynamic behavior of photogenerated carriers are inherently limited by their poor spatial resolution and large penetration depth. Herein, we develop an ultrafast scanning electron microscope (USEM) with a planar emitter. The photoelectrons per pulse in this USEM can be two orders of magnitude higher than that of a tip emitter, allowing the capture of high-resolution spatiotemporal images. We used the contrast change of the USEM to examine the dynamic nature of surface carriers in an InGaAs/InP avalanche photodiode (APD) after femtosecond laser excitation. It was observed that the photogenerated carriers showed notable longitudinal drift, lateral diffusion, and carrier recombination associated with the presence of photovoltaic potential at the surface. This work demonstrates an in situ multiphysics USEM platform with the capability to stroboscopically record carrier dynamics in space and time.

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Section: Instrumentsmentioning

confidence: 99%

Spatiotemporal Visualization of Photogenerated Carriers on an Avalanche Photodiode Surface Using Ultrafast Scanning Electron Microscopy

Tian,

Yang,

et al. 2024

Nanomaterials

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“…1 An NEA photocathode has advantages over TEs and FEs; e.g., it has a low transverse energy of 34 meV and high electron-beam current generation of 9.5 mA, enabling them to realize a highbrightness electron beam of 4.2 × 10 7 Am −2 sr −1 V −1 . [2][3][4] Furthermore, the NEA photocathode generates a 2.4 ps high-speed pulsed electron beam and a 100 multi-electron beam, which TE and FE cannot achieve. 5,6 The quantum efficiency (QE) of the NEA photocathode gradually decreases during use.…”

Section: Introductionmentioning

confidence: 99%

Novel electron beam technology using InGaN photocathode for high-throughput scanning electron microscope imaging

Koizumi

Shikano

Noda

et al. 2023

Metrology, Inspection, and Process Control XXXVII

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An InGaN photocathode with a negative electron affinity (NEA) surface is suitable for industrial use because of features such as a long quantum efficiency lifetime, availability with a visible laser as an excitation light source, and the presence of a transmission-type structure. The first objective is the development of an InGaN photocathode electron gun that can be mounted on a scanning electron microscope (SEM) and the evaluation of the electron beam size at the emission point, maximum emission current, and transverse energy of the electron beam, which are important factors for realizing a high probe current in the SEM. The second objective is the evaluation of emission current stability, while the third objective is the generation of a pulsed electron beam and multi-electron beam from the InGaN photocathode. The parameters of the electron beam from the photocathode electron gun were an emission beam radius of 1 μm, transverse energy of 44 meV, and an emission current of up to 110 μA. Using a high beam current with low transverse energy from the photocathode, a 13 nA probe current with 10 nm SEM resolution was observed with 15 μA emission. At 15 μA, the continuous electron beam emission for 1300 h was confirmed; at 30 μA, the cycle time between the NEA surface reactivations was confirmed to be 90 h with 0.043% stability. Moreover, a 4.4 ns pulsed e-beam with a 4.7 mA beam current was generated, and a 5 × 5 multielectron beam with 12% uniformity was then obtained. The advantages of the InGaN photocathode, such as high electron beam current, low transverse energy, long quantum efficiency lifetime, pulsed electron beam, and multi-electron beam, are useful in industries including semiconductor device inspection tools.

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Exploring metal-supported few-layer graphene for photocathode application through Cs/O activation process

Zhang

Zhan

et al. 2022

Journal of Materials Research and Technology

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Brightness evaluation of pulsed electron gun using negative electron affinity photocathode developed for time-resolved measurement using scanning electron microscope

Cited by 9 publications

References 15 publications

Spatiotemporal Visualization of Photogenerated Carriers on an Avalanche Photodiode Surface Using Ultrafast Scanning Electron Microscopy

Spatiotemporal Visualization of Photogenerated Carriers on an Avalanche Photodiode Surface Using Ultrafast Scanning Electron Microscopy

Novel electron beam technology using InGaN photocathode for high-throughput scanning electron microscope imaging

Exploring metal-supported few-layer graphene for photocathode application through Cs/O activation process

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