Scanning ultrafast electron microscopy reveals photovoltage dynamics at a deeply buried 
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 interface

Ellis, Stephen R.; Bartelt, N. C.; Léonard, François; Celio, Kimberlee Chiyoko; Fuller, Elliot James; Hughart, David Russell; Garland, Diana R.; Marinella, M. J.; Michael, Joseph R.; Chandler, David W.; Liao, Bolin; Talin, A. Alec

doi:10.1103/physrevb.104.l161303

Cited by 12 publications

(10 citation statements)

References 20 publications

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“…In our recent work ( 33 ), we have shown that the material response is well reproduced by modeling the one-dimensional (1D) diffusion of charge carriers near a surface treated as a saturable adsorption boundary condition (details provided in section S10). As such, we can consider surface traps forming a density of photoexcited charge carriers ρ cc ( t , z ) where z is in the vertical direction, to prepare an initial condition ofnormalρccfalse(0,Zfalse)=fhνe−αzwhere f , ν, and α are the fluence, frequency of light, and attenuation coefficient, respectively, albeit the exponential term is not applied in these analyses.…”

Section: Resultsmentioning

confidence: 99%

“…The differences in carrier mobilities and concentrations could thus offset each other and may account for the similarity in timescales of dynamics observed in these studies. Other material properties will also affect these dynamics, most notably surface structure (17,33,(48)(49)(50)(51), which will have effects on other processes such as Fermi-level pinning. Such differences likely account for the observed differences in the contrast mechanisms and the dynamics between various SUEM studies on GaAs (39,40).…”

Section: Discussionmentioning

confidence: 99%

“…2A as a simplified schematic. A preliminary version of the SUEM was described in our prior work ( 33 ). Here, a 1064-nm laser source (2-MHz repetition rate, 10-ps pulses) was coupled to a Philips-FEI XL30s SEM through optical ports that were built onto the SEM chamber and the field-emission gun.…”

Section: Introductionmentioning

confidence: 99%

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Picosecond carrier dynamics in InAs and GaAs revealed by ultrafast electron microscopy

Perez,

Ellis,

Alcorn

et al. 2024

Sci. Adv.

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Understanding the limits of spatiotemporal carrier dynamics, especially in III-V semiconductors, is key to designing ultrafast and ultrasmall optoelectronic components. However, identifying such limits and the properties controlling them has been elusive. Here, using scanning ultrafast electron microscopy, in bulk n-GaAs and p-InAs, we simultaneously measure picosecond carrier dynamics along with three related quantities: subsurface band bending, above-surface vacuum potentials, and surface trap densities. We make two unexpected observations. First, we uncover a negative-time contrast in secondary electrons resulting from an interplay among these quantities. Second, despite dopant concentrations and surface state densities differing by many orders of magnitude between the two materials, their carrier dynamics, measured by photoexcited band bending and filling of surface states, occur at a seemingly common timescale of about 100 ps. This observation may indicate fundamental kinetic limits tied to a multitude of material and surface properties of optoelectronic III-V semiconductors and highlights the need for techniques that simultaneously measure electro-optical kinetic properties.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Picosecond carrier dynamics in InAs and GaAs revealed by ultrafast electron microscopy

Perez,

Ellis,

Alcorn

et al. 2024

Sci. Adv.

Self Cite

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“…Indeed, taking the peak distance of 81 µm from the edge of the beam radius (30 µm) as the diffusion length and 43 ps as the time, the expected diffusion coefficient for this rapid expansion would be on the order of 6 × 10 5 cm 2 /s. Furthermore, the signal outside of the laser spot is not generated by the pump laser pulse itself, as the fluence 81 µm away in the major axis is 5 × 10 -3 µJ/cm 2 , far below the values required to see any signal at all 36 . The peak distance by itself is three times the size of the laser spot size, suggesting that the charge carriers rapidly spread through ballistic transport of hot carriers or ultrafast diffusion 31,39 .…”

Section: Introductionmentioning

confidence: 93%

“…Despite the 38% increase in counts, the minority carrier concentration only increases by 10 18 cm -3 . There is some discussion on the charge carriers inducing a band-bending effect at the oxide-semiconductor interface which increases the SE emission, but further experiments are required to fully understand the large change in counts 36 .…”

Section: Introductionmentioning

confidence: 99%

Development of an ultrafast pulsed ponderomotive phase plate for cryo-electron tomography

Du,

Bartnik,

Duncan

et al. 2024

Preprint

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Cryo-electron tomography (cryo-ET) is a powerful modality for resolving cellular structures in their native state. While single-particle cryo-electron microscopy (cryo-EM) excels in determining protein structures purified from recombinant or endogenous sources, cryo-ET suffers from low contrast in crowded cellular milieux. A novel experimental approach to enhance contrast in cryo-ET is to manipulate the phase of scattered pulsed electrons using ultrafast pulsed photons. Here, we outline the experimental design of a proof-of-concept electron microscope and demonstrate synchronization between electron packets and laser pulses. Further, we show ultrabright photoemission of electrons from an alloy field emission tip using femtosecond ultraviolet pulses. These experiments pave the way towards exploring the utility of the ponderomotive effect using pulsed radiation to increase phase contrast in cryo-ET of subcellular protein complexes in situ, thus advancing the field of cell biology.

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Research on the Evolution of Defects Initiation and the Diffusion of Dopant on the Si/SiO₂ Interface

Yang,

Chen,

et al. 2024

Adv Materials Inter

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Si/SiO2 interfaces, important parts of Si‐based devices, significantly influence the performance of Si‐based devices. However, owing to the impact of the external environment, related defects are generated, and the dopant can diffuse and redistribute, causing a series of parasitic effects that reduce the lifespan of the devices. In this paper, recent investigations on the mechanisms of interface defect initiation and dopant diffusion are systematically reviewed. At the Si/SiO2 interface, Pb‐type center defects are identified, including Pb, Pb0, and Pb1 center defects. Near the interface, E’ center defects are identified, and H‐related defects are also formed. In addition, dopant ions are introduced in the Si/SiO2 interface to improve the conductivity. However, during the oxidation process, the dopant ions can diffuse and redistribute at the interface. Investigations of the dopant diffusion mechanism, modeling, and dopant pile‐up are reviewed in this paper. Comparisons and discussions of the initial mechanism of defects, structures of defects, and dopant diffusion mechanisms are presented to provide valuable guidance for improving the performance and extending the lifespan of Si/SiO2 interfaces. Finally, an outlook is presented, including improving the models of interface defects to better protect against local strains and multienvironment impacts, and developing 3D detection technology for dopants.

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Scanning ultrafast electron microscopy reveals photovoltage dynamics at a deeply buried p−Si/SiO2 interface

Cited by 12 publications

References 20 publications

Picosecond carrier dynamics in InAs and GaAs revealed by ultrafast electron microscopy

Picosecond carrier dynamics in InAs and GaAs revealed by ultrafast electron microscopy

Development of an ultrafast pulsed ponderomotive phase plate for cryo-electron tomography

Research on the Evolution of Defects Initiation and the Diffusion of Dopant on the Si/SiO₂ Interface

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Scanning ultrafast electron microscopy reveals photovoltage dynamics at a deeply buried p−Si/SiO2 interface

Cited by 12 publications

References 20 publications

Picosecond carrier dynamics in InAs and GaAs revealed by ultrafast electron microscopy

Picosecond carrier dynamics in InAs and GaAs revealed by ultrafast electron microscopy

Development of an ultrafast pulsed ponderomotive phase plate for cryo-electron tomography

Research on the Evolution of Defects Initiation and the Diffusion of Dopant on the Si/SiO2 Interface

Contact Info

Product

Resources

About

Research on the Evolution of Defects Initiation and the Diffusion of Dopant on the Si/SiO₂ Interface