B.S. Dassanayake

Tunable optoelectronic properties of CBD-CdS thin films via bath temperature alterations

The tunability of the band-gap value and electron affinity of the n-CdS by adjusting the growth parameters is very important as it paves the way to improve the efficiency of CdS-based solar cells by adjusting the band lineup with other p-type semiconductors. In this respect, polycrystalline n-CdS thin films were grown on FTO glass substrates at different bath temperatures (40–80 °C) by the chemical bath deposition technique. The structural, morphological and optoelectronic properties of CdS thin films were studied using x-ray diffraction, scanning electron microscopy, UV-Vis spectrometry, profilometry, atomic force microscopy, photoelectrochemical and Mott–Schottky measurements. Absorption measurements reveal that an energy-gap value of n-CdS can be adjusted from 2.27 to 2.57 eV and Mott–Schottky measurements indicate that the flat-band potential is increased from −699 to −835 V with respect to a Ag/AgCl electrode by decreasing the deposition bath temperature from 60 to 40 °C. This tunability of optoelectronic properties of n-CdS is very useful for applications in thin film solar cells and other devices.

Inelastic Transmission Of Electrons Through A Single Macro‐Glass Capillary And Secondary Electron Emission

The transmission of electrons with incident energies 300–1000 eV through single glass capillary samples of macroscopic dimensions has been investigated. The transmitted spectra for all energies indicate dominance of inelastic electrons as the tilt angle ψ increases, with the ratio of inelastically to elastically transmitted intensity for tilt angles >2.5° (the indirect region of transmission) reaching a constant value of about 2:1. When the secondary electron emission was analyzed, higher yield was observed with decreasing primary beam energy and with increasing sample tilt angle.

Dependence of electron transmission on charge deposited in tapered glass macrocapillaries at a tilt angle of 5.0

The characteristics of charge deposited (time) into a tapered glass capillary were studied for an incident energy of ? 1025?eV at a tilt angle of 5?. Electron beams resulting in intensities of 1.5?7000?nC deposited into a tapered borosilicate glass capillary were investigated for inlet/outlet diameters of 800/100??m. The electron transmission consisted of stable transmission, fluctuations, blocking and self-discharging associated with a sudden rise of?transmission as deposited charge was ejected from the capillary. In the case of stable transmission, it was found to be due to both elastic and inelastic contributions, with inelastic transmission dominant.

Transmission of fast highly charged ions through straight and tapered glass capillaries

The transmission of 1 and 3 MeV protons through a borosilicate straight glass capillary and a tapered glass capillary was investigated. The straight capillary had a diameter of ~0.18 mm and a length of ~14.4 mm, while the tapered capillary had an inlet diameter of ~0.71 mm, an outlet diameter of ~0.10 mm and a length of ~28 mm. The results show that the 1 and 3 MeV protons traverse through both samples without energy loss, while the tapered capillary showed better transmission than the straight capillary.

Transmission and guiding of fast electrons through insulating PET nanocapillaries

Transmission and guiding of electrons traveling through insulating PET nanocapillaries were measured for different sample tilt angles at the energies of 500 and 800 eV. Direct transmission and guiding and the transition between the two regions were observed for angles near zero degrees. Elastic and inelastic spectra and a combination of the two were seen in the different regions.

Guiding of electrons and fast ions through insulating nanocapillaries

We report new measurements of the transmission and guiding of 350, 500, and 800 eV electrons through insulating polyethylene terephthalate (PET) polymer nanocapillaries. For 800 eV the onset of guiding is found to occur at a foil tilt angle of 3°, while the results for 350 and 800 eV, combined with previous results, show the direct transmission properties for incident electron energies ranging from 250–1000 eV. Also, transmission of 16 MeV O5+ ions through the same PET foil was studied. Transmitted O5+ ions were found to lose energy and change charge upon traversing the nanocapillaries.

Interference effects in electron emission spectra for 3 MeV/u H+ + O2 collisions

The present work extends the study of oscillatory structures associated with electron emission from diatomic molecular targets to 3 MeV/u H+ + O2. Electrons ejected from O2 were detected in the energy range 5 to 400 eV and for observation angles 30°, 60°, 90° and 150°. Experimental molecular O2 cross sections normalized to theoretical molecular O2 cross sections reveal oscillatory structures suggestive of secondary interferences as evidenced by their independence on the observation angle. Contrary to results for 1, 3 and 5 MeV/u H+ + H2, no obvious evidence for primary Young-type interferences was seen, a result similar to that found for H+ + N2 collisions.

Interferences associated with electron emission from O2 by fast ions compared with H2 and N2

Oscillatory structures associated with electron emission from O2 by 3 MeV/u H2 and 1.9 MeV/u O5,82impact are analyzed and compared with results for H2 and N2. Measured molecular O2 cross sections normalized to theoretical molecular O2 cross sections indicate oscillations suggestive of second-order interferences. Contrary to previous findings for H2 targets, no evidence of first-order interferences was revealed. The results are in qualitative agreement with recent observations for 3 MeV/u H2 2 N2 collisions, where a strong suppression of the primary Young-type interferences was also reported.