Subsurface excitations in a metal

Ray, M.P.; Lake, Russell; Sosolik, C. E.; Thomsen, Lasse Bjørchmar; Nielsen, Gunver; Chorkendorff, Ib; Hansen, Ole

doi:10.1103/physrevb.80.161405

Cited by 6 publications

(6 citation statements)

References 27 publications

(30 reference statements)

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“…This is a correlation in energy-dependent behavior, and hence this does not indicate a causal relationship between the penetration depth and the measured yield. Preliminary measurements using incident species other than He + agree with the theoretical model outlined in the manuscript and further suggest that the hot electrons are generated at the surface of the device as we have proposed [26]. Prior measurements of subthreshold electron emission external to a solid target have utilized the Falcone-Sroubek theory which is an extension of the concept of linear stopping power that is based on nonadiabatic interactions between the projectile ion and the metal atoms [19,20,27,28].…”

Section: Surface Assisted Electron Excitationssupporting

confidence: 61%

Towards hot electron mediated charge exchange in hyperthermal energy ion–surface interactions

Ray

Lake

Thomsen

et al. 2010

J. Phys.: Condens. Matter

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We have made Na (+) and He (+) ions incident on the surface of solid state tunnel junctions and measured the energy loss due to atomic displacement and electronic excitations. Each tunnel junction consists of an ultrathin film metal-oxide-semiconductor device which can be biased to create a band of hot electrons useful for driving chemical reactions at surfaces. Using the binary collision approximation and a nonadiabatic model that takes into account the time-varying nature of the ion-surface interaction, the energy loss of the ions is reproduced. The energy loss for Na (+) ions incident on the devices shows that the primary energy loss mechanism is the atomic displacement of Au atoms in the thin film of the metal-oxide-semiconductor device. We propose that neutral particle detection of the scattered flux from a biased device could be a route to hot electron mediated charge exchange.

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Section: Surface Assisted Electron Excitationssupporting

confidence: 61%

Towards hot electron mediated charge exchange in hyperthermal energy ion–surface interactions

Ray

Lake

Thomsen

et al. 2010

J. Phys.: Condens. Matter

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“…This direction of current flow is also consistent with previous measurements. 1,2,5,6,15 To obtain a value for the hot electron current generated, we subtracted the response of the device from the baseline background signal. For the data shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Typically, for exoelectron emission, a threshold is observed within the "kinetic electron excitation" (KEE) model, 5 which can be thought of as an ion-analog for the photoelectric effect where electron emission from a metal surface into the vacuum arises due to ion bombardment instead of photon bombardment. In the KEE model, the metal surface is idealized as a Fermi gas, and a threshold ion velocity (v th ) for exoelectron emission, analogous to the photon frequency in the photoelectric effect, is calculated taking into account energy transfer to the electronic system of the metal by binary collisions and the depth of the potential The label ON signifies that the beam was directed onto the device face (e.g., at t % 10 s), while OFF signifies it was deflected away from the device face (e.g., at t % 130 s).…”

Section: Resultsmentioning

confidence: 99%

Probing kinetically excited hot electrons using Schottky diodes

Kulkarni

Field

Cutshall

et al. 2017

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Hot electron generation was measured under the impact of energetic Ar and Rb ions on Ag thin film Schottky diodes. The energy-and angular-dependence of the current measured at the backside of the device due to ion bombardment at the frontside is reported. A sharp upturn in the energy dependent yield is consistent with a kinetic emission model for electronic excitations utilizing the device Schottky barrier as determined from current-voltage characteristics. Backside currents measured for ion incident angles of 630 are strongly peaked about 0 (normal incidence) and resemble results seen in other contexts, e.g., ballistic electron emission microscopy. Accounting for the increased transport distance for excited charges at non-normal incidence, the angular results are consistent with the accepted mean free path for electrons in Ag films. V

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“…of the target material. There can be changes in electrical, [25][26][27] optical, and thermal properties of the materials. However, in all the aforementioned applications people have so far considered mainly single and broad ion beams (diameter ≥ 0.1 -2 cm) where localized phenomena and tailoring of local surfaces and subsurface layers cannot be carried out.…”

Section: Introductionmentioning

confidence: 99%

“…The interaction of low energy ion beams with matter is quite different from that of high energy ion beams. High energy ion beams are able to sputter, 4 channel, 5 deposit deep inside, and backscatter from substrates 6 etc because of its higher range inside the materials, 7,8 patterning, and generation of internal subsurface excitations [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] etc. Since low energy ion beams cannot penetrate deep inside the substrate therefore its interaction is mainly limited to surface and sub-surface layers.…”

Section: Introductionmentioning

confidence: 99%

Localized subsurface modification of materials using micro-low-energy multiple ion beamlets

Chowdhury

Bhattacharjee

2011

AIP Advances

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Generation of focused multiple ion beamlets from an intense microwave plasma source is investigated for the creation of localized subsurface modification of materials. Unlike conventional single element focused ion beam (FIB) systems, the plasma source is capable of providing ion beams of multiple elements. Two types of plasma electrodes (PE) are employed, one with a honeycomb structure with notched apertures and another with a 5×5 array of through apertures, both attached to the plasma source and are capable of generating focused ion beamlets (50 - 100 μm diameter) in a patterned manner. Measurements of ion saturation current near the PE indicate that the plasma is uniform over an area of ∼ 7 cm2, which is further confirmed by uniformity in extracted beam current through the apertures. The ion beams are applied to investigate change in electrical sheet resistance Rs of metallic thin films in a controlled manner by varying the ionic species and beam energy. Results indicate a remarkable increase in Rs with beam energy (∼ 50 % at 1 keV for Ar ions), and with ionic species (∼ 90% for Krypton ions at 0.6 keV), when 80 nm thick copper films are irradiated by ∼2 cm diameter ion beams. Ion induced surface roughness is considered as the main mechanism for this change as confirmed by atomic force microscopy (AFM) measurements. Predictions for micro-beamlet induced change in Rs are discussed. The experimental results are verified using TRIM and AXCEL-INP simulations

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Subsurface excitations in a metal

Cited by 6 publications

References 27 publications

Towards hot electron mediated charge exchange in hyperthermal energy ion–surface interactions

Towards hot electron mediated charge exchange in hyperthermal energy ion–surface interactions

Probing kinetically excited hot electrons using Schottky diodes

Localized subsurface modification of materials using micro-low-energy multiple ion beamlets

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