Spatial Distribution of the Fluorescent Radiation Emission Caused by an Electron Beam

Cohn, Arthur; Caledonia, G. E.

doi:10.1063/1.1659505

Cited by 72 publications

(30 citation statements)

References 15 publications

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“…3 as a series of isoionization contours. These contours were determined experimentally for ionization within a gaseous target by Cohn and Caledonia (1970) and have since been found to be accurate for silicon targets (Possin and Norton 1975;Possin 1977). Quite similar results have also been obtained by computation (Bishop 1965;Shimizu and Everhart 1972).…”

Section: Excitation Of Semiconductors By Energetic Electronssupporting

confidence: 59%

“…This is accomplished, by analogy with the case for bulk material, by assuming that R at the surface or boundary is proportional to the product of trap density per unit area, capture cross section per trap, and the thermal velocity. This quantity has dimensions of cm/sec and is consequently known as the surface or boundary recombination velocity S. The minority carrier flux that is absorbed at a surface of recombination velocity S is therefore: The distance scale is normalized to R, and the generation rate is shown as contours of equal ionization rate (Cohn and Caledonia 1970). + S.J p, and the appropriate boundary condition for diffusion to the surface is:…”

Section: Excitation Of Semiconductors By Energetic Electronsmentioning

confidence: 99%

See 1 more Smart Citation

Charge collection scanning electron microscopy

Leamy¹

1982

Journal of Applied Physics

772

320

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A novel apparatus for in situ compression of submicron structures and particles in a high resolution SEM Rev. Sci. Instrum. 83, 095105 (2012) Foucault imaging by using non-dedicated transmission electron microscope Appl. Phys. Lett. 101, 093101 (2012) New Products Rev. Sci. Instrum. 83, 079501 (2012) Towards secondary ion mass spectrometry on the helium ion microscope: An experimental and simulation based feasibility study with He+ and Ne+ bombardment This review encompasses the application of the scanning electron microscope to the study and characterization of semiconductor materials and devices by the Electron Beam Induced Conductivity (EBIC) method. In this technique, the charge carriers generated by the electron beam of the microscope are collected by an electric field within the material and sensed as a current in an external circuit. When employed as the video signal of the SEM, this collected current image reveals inhomogeneities in the electrical properties of the material. The technique has been used to determine carrier lifetime, diffusion length, defect energy levels, and surface recombination velocities. Charge collection images reveal the location of p-n junctions, recombination sites such as dislocations and precipitates, and the presence of doping level inhomogeneities. Both the theoretical foundation and the practical aspects of these effects are discussed in a tutorial fashion in this review. PACS numbers: 07.80. + x, 61.16.Di, 72.20. -i GLOSSARY OF SYMBOLS C = ill II = image contrast. {j = SrlL = recombination velocity -;-diffusion velocity. D, De' Dh = Diffusion coefficient (D) for electrons (De), and for holes (D h ) (cm2/sec). E = electron beam energy (eV). Eeh = carrier pair creation energy (eV). E bg = band-gap energy (eV). ET = carrier trap energy level (eV). S = electric field strength (V Icm). E = dielectric constant. f = energy fraction of the incident electron beam that is reflected from the sample surface. g = carrier pair generation rate (cm -3).I = electric current (amps). Ib = SEM electron beam current (amps). Ig = IbE(1 -f)IEeh = maximum beam generated current (amps). Icc = collected current (short circuit current) (amps). Is = saturation current of a p-n junction (amps). J e , J h = electron (J e ) or hole (J h ) flux (cm-2 sec-I ). k = Boltzmann's constant = 1.38 X 10-23 I/'K. Leo L h = diffusion length for electrons (L e) and holes (L h ) (cm). m = mass (gms). n = equilibrium electron density (cm -3). iln = excess electron density (cm-3 ). NT = carrier trap density (cm-3 ). NB = net ionized impurity density (cm-3 ). p = equilibrium hole density (cm -3). ilp = excess hole density (cm -3). q = electronic charge = 1.6 X 10-19 C. R = recombination rate (sec-I).R e = electron range (cm). p = density (gm/cm 3 ). S = surface recombination velocity (cm/sec). l: = charge collection efficiency. 0', U e , Uh = capture cross section (0') for electrons (u e ) and holes (u h ) (cm 2 ). T = temperature (OK). T, T e , Th = lifetime (T) for electrons (Te) and for holes (T h ) (sec). T...

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Section: Excitation Of Semiconductors By Energetic Electronssupporting

confidence: 59%

Section: Excitation Of Semiconductors By Energetic Electronsmentioning

confidence: 99%

Charge collection scanning electron microscopy

Leamy¹

1982

Journal of Applied Physics

772

320

View full text Add to dashboard Cite

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“…[9][10][11] The application of air scintillation for dosimetry of electron beams from a van de Graaff accelerator (0.5-1.5 MeV) has also been reported 12 and kilovoltage electron beams have been photographed using this phenomenon. 13 However, to the best of our knowledge, air scintillation has never been considered in the context of the clinical use of modern medical linear accelerators. In this paper, we report images of air scintillation induced by megavoltage electron beams and kilovoltage x-ray beams and suggest that this phenomena may be useful for characterizing and monitoring therapeutic radiation beams.…”

Section: Introductionmentioning

confidence: 99%

“…21 Cherenkov radiation has a broad emission spectrum that spans the entire ultraviolet and visible spectrum. In air, given the low index of refraction, electrons must have energy greater than 20.3 MeV to produce Cherenkov radiation, which is beyond the range of most medical linear accelerators (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). Several studies have however utilized Cherenkov radiation generated in water and tissue for dosimetry [22][23][24][25] and molecular imaging.…”

Section: Introductionmentioning

confidence: 99%

Seeing the invisible: Direct visualization of therapeutic radiation beams using air scintillation

et al. 2013

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Purpose: To assess whether air scintillation produced during standard radiation treatments can be visualized and used to monitor a beam in a nonperturbing manner. Methods: Air scintillation is caused by the excitation of nitrogen gas by ionizing radiation. This weak emission occurs predominantly in the 300-430 nm range. An electron-multiplication chargecoupled device camera, outfitted with an f/0.95 lens, was used to capture air scintillation produced by kilovoltage photon beams and megavoltage electron beams used in radiation therapy. The treatment rooms were prepared to block background light and a short-pass filter was utilized to block light above 440 nm. Results: Air scintillation from an orthovoltage unit (50 kVp, 30 mA) was visualized with a relatively short exposure time (10 s) and showed an inverse falloff (r 2 = 0.89). Electron beams were also imaged. For a fixed exposure time (100 s), air scintillation was proportional to dose rate (r 2 = 0.9998). As energy increased, the divergence of the electron beam decreased and the penumbra improved. By irradiating a transparent phantom, the authors also showed that Cherenkov luminescence did not interfere with the detection of air scintillation. In a final illustration of the capabilities of this new technique, the authors visualized air scintillation produced during a total skin irradiation treatment. Conclusions: Air scintillation can be measured to monitor a radiation beam in an inexpensive and nonperturbing manner. This physical phenomenon could be useful for dosimetry of therapeutic radiation beams or for online detection of gross errors during fractionated treatments.

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“…The position of its maximum is the so-called energy deposition depth r E . The literature on the stopping of low-energy electron beams 17,18 shows that this energy deposition depth scales with electron energy E ͑in keV͒ as…”

Section: Scaling Of Pumping Power Density With Electron Energymentioning

confidence: 99%

Lasers in dense gases pumped by low-energy electron beams

Ulrich

Niessl

Wieser

et al. 1999

Journal of Applied Physics

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Articles you may be interested inInhibiting spontaneous etching of nanoscale electron beam induced etching features: Solutions for nanoscale repair of extreme ultraviolet lithography masks The use of low-energy ͑Ϸ15 keV͒ electron beams for pumping laser systems in dense gases with high specific power deposition is described. Thin ͑300 nm͒ SiN x ceramic foils used as entrance window in a transverse geometry for the electron beam allows pressure differentials of several atmospheres with low percentage energy loss in transmission. The 1.73 m XeI (5d͓3/2͔ 1 -6p͓5/2͔ 2 ) infrared laser was used for a first demonstration of this concept. The laser operated between 130 and 650 mbar. A threshold pumping power of 5.3 W and a maximum output power of 6 mW were observed. The system can be scaled to high pumping power ͑ϷMW/cm 3 ͒ and short wavelength.

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Spatial Distribution of the Fluorescent Radiation Emission Caused by an Electron Beam

Cited by 72 publications

References 15 publications

Charge collection scanning electron microscopy

Charge collection scanning electron microscopy

Seeing the invisible: Direct visualization of therapeutic radiation beams using air scintillation

Lasers in dense gases pumped by low-energy electron beams

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