Electron emission from ion-bombardedSiO2thin films

Abstract

The electron yield from SiOz films on Si was measured as a function of oxide thickness and ion energy for 150 -300 keV H+, He+, N+, Ne+, Ar+, Kr+, and Xe+ ions. For oxide films thicker than 200 A, the electron yield was found to be approximately independent of oxide thickness. The electron yield from the thick oxide increased as a function of the energy deposited D in electronic excitations with approximately the form D ' and not D as expected from theory. Close to the Si02/Si interface, unexpected variations in the electron yield with oxide thickness, dependent on ion mass and energy, were found. Experiments were performed to investigate whether or not the oxide surface was charged by the ion beam, but such effects could not be observed. However, a satisfactory interpretation of the data could be obtained with a model previously suggested for explaining the dependence of the electron yield on the angle of ion incidence. In this model, the positive charge left behind in the oxide by the liberated electrons within the electron cascades of individual ions, causes the probability of escape of electrons to decrease with increasing electron yield.

Comparative study of multifragmentation of gold nuclei induced by relativistic protons, 4He, and 12C

“…A self-supporting Au target 1.5 mg/cm 2 was located in the center of the FASA vacuum chamber (∼ 1 m in diameter). The following beams were used: protons at energies of 2.16, 3.6 and 8.1 GeV, 4 He at energies of 4 and 14.6 GeV and 12 C at 22.4 GeV. The average beam intensity was 7 · 10 8 p/spill for protons and helium and 1 · 10 8 p/spill for carbon projectiles with a spill length of 300 ms and a spill period of 10 s.…”

“…Later on, in the fifties, this phenomenon was observed in accelerator experiments [3] and then studied leisurely for three decades. The situation changed dramatically in 1982 when multiple emission of IMF's was discovered in the 12 C (1030 MeV) irradiation of emulsion at the CERN synchrocyclotron [4]. These findings stimulated the development of many theoretical models to put forward the attractive idea that copious production of IMF's may be related to a liquid-gas phase transition in nuclear matter [5][6][7][8][9].…”

“…Light relativistic projectiles provide therefore a unique possibility for studying "thermal multifragmentation". It has been shown that thermal multifragmentation indeed takes place in collisions of light relativistic projectiles (p,p, 3 He, 4 He, π − ) with a heavy target, and fragments are emitted from a diluted excited residue after an expansion driven by thermal pressure [11][12][13][14][15][16]. From IMF-IMF correlation data, fragment emission times of less than 100 fm/c have been deduced [17][18][19].…”

Electron emission and defect formation in the interaction of slow, highly charged ions with diamond surfaces

“…-4 cm 2 /Vs for SiO 2 [16]. Do to the low fluences applied here, we were not able to probe the recently detailed hole trapping effect on electron emission from poly-crystalline diamond surfaces [17].…”

Filtering of the interstellar dust flow near the heliopause: the importance of secondary electron emission for the grain charging

“…Furthermore, measured yield data involve the primary electrons reflected at the sur- Katz et al (1977), and empirical formula of Draine and Salpeter (1979), respectively. Open circles denote experimental data of silicate by Jacobsson (1993) and Jacobsson and Holmén (1994) with assumptions of δ m = 4.0 and E m = 90 keV from the similarity of the slopes between the secondary electron yield and the stopping power (ICRU, 1993). Closed circles denote experimental data of carbon by Meckbach et al (1975) with δ m = 4.0 at E m = 20 keV, Hasselkamp et al (1990) with δ m = 1.7 at E m = 85 keV, Gelfort et al (1997) with δ m = 3.24 at E m = 70 keV, and Ritzau and Baragiola (1998) with δ m = 2.9 at E m = 85 keV.…”