Surface Conductivity of Borosilicate Glass

Abstract

An electron beam projected onto a clean glass surface in vacuum is blown up by deceleration caused by the high surface charge accumulated, thus spreading the beam on a very short time scale before arrival on the surface. Arriving at the surface, electrons are rapidly bound to lattice imperfections (not adsorbed gas atoms) presumably creating O− ions. Thereupon, spread of the charge along and through the surface, progresses by movement of labile alkali ions which combine with the surface O− ions, leaving their initial negative O− partners behind in the glass. The rapid transfer of the negative charge from the surface to the interior of the glass, where it encounters dielectric screening, causes a temporary positive displacement current which masks the displacement current due to the discharge movement to the grounded electrode. It has a maximum value immediately following the electron beam cutoff, and declines approximately exponentially with a time constant τ, of about 0.1 sec for the range of electron surface charge densities, computed from beam cross sections ranging from 1010−3×1011 electrons/cm2. Thereafter, the charge leaks off as a volume conduction current on a time scale of tens of minutes. There is no surface conduction by free electrons, and surface conductivity of clean glass is low and comparable with volume conductivity. High apparent plasma induced surface conductivity lies in the plasma, and not in the glass.

Work Function Modification in P3HT H/J Aggregate Nanostructures Revealed by Kelvin Probe Force Microscopy and Photoluminescence Imaging

“…We used Platinum Silicide probes and calibrated the tip work function (∼5.5 eV) from KPFM on evaporated gold substrates. We also measured the average surface potential of floating cover glass to be about +0.6 eV (relative to Pt tip), which corresponds to work function value of 4.9 eV consistent with the UPS measurements …”

Morphology-Dependent Electronic Properties in Cross-Linked (P3HT-b-P3MT) Block Copolymer Nanostructures

“…þ600 meV, whose work function is also known from UPS to be 4.9À5.0 eV. 34 This places the nominal HOMO level of cross-linked nanoribbons at about À4.872 eV. This value falls within the range of reported HOMO energy level of solvated P3HT in toluene and chloroform (between À4.8 and À5.2) determined from cyclic voltammetry measurements.…”

Charge deposition, redistribution, and decay properties of insulating surfaces obtained from guiding of low-energy ions through capillaries

“…conductivities of Pyrex borosilicate glass [13,37]. This yields a surface relaxation time of τ s = ε 0 R 1 κ s = 5.2 s. By the use of (6b), we see that the dipole relaxation rate τ −1 1 = 0.82 270 + 0.17 5.2 = 3.0 + 32.7 mHz is dominated by the surface channel.…”

“…Our model has two free parameters, namely, the bulk and surface conductivities. We took for the bulk conductivity of borosilicate at room temperature the typical value of κ b = 1.5 × 10 −15 S/cm [13,37], yielding a characteristic bulk depletion time of τ b = ε 0 ε r κ b 270 s. The surface conductivity in borosilicate is not a well-known quantity and depends strongly on any adsorbed impurities. At room temperature, it is typically less than 10 −15 S in dry environment.…”