XPS AND UPS investigation of NH/sub 4/OH-exposed Cu(In,Ga)Se/sub 2/ thin films
Photoelectron spectroscopy was used to determine the compositional and electronic changes occurring in Cu(In,Ga)Se/sub 2/ thin films as a result of immersion in aqueous ammonia solution. We find that NH/sub 4/OH-treated CIGS surfaces are preferentially etched of indium and gallium, resulting in the formation of a thin layer of a degenerate Cu-Se compound that we tentatively identify as Cu/sub 2/Se. The work function of ammonia-treated samples is found to increase by 0.6 eV relative to as-grown CIGS thin films. The uniformity of chemical bath effects (etching & deposition) was found to be improved by the addition to the bath of a non-ionic surfactant. Initial device results show that the new surfactant-based chemical bath deposition (CBD) method may lead to better and thinner CdS buffer layers.
Comparative Photoemission Study of the CuInC 2VI Chalcopyrite Compounds
Photoemission spectra of all CuInC2VI chalcopyrite compounds are measured at Hel line excitation and of CuInS2 also at excitation with ZrMζ radiation. It is found that the In5s – chalcogen p bonding states shift to lower binding energies with increasing anion mass. The energetic position of the S3s band of CuInS2 is also determined. The experimental results obtained are compared with previous measurements and with theoretical band structure calculations. 
 
 
 
Photoemissionsspektren aller CuInC2VI – Chalkopyritverbindungen wurden bei Hel-Anregung und von CuInS2 auch bei Anregung mit ZrMζ-Strahlung gemessen. Es zeigt sich, das sich die In5s-Chalkogen p-Bindungszustande mit steigender Anionenmasse nach kleineren Bindungsenergien verschieben. Die energetische Lage des S3s-Bandes im CuInS2 wurde im ebenfalls bestimmt. Die erhaltenen experimentellen Ergebnisse werden mit fruheren Messungen und mit theoretischen Bandstrukturberechnungen verglichen.
Verification of CuInSe2 density of states features by reflection electron energy loss spectroscopy
Reflection electron energy loss measurements of CuInSe2 single crystals are reported and when possible, the losses are compared with former results by Kazmerski and Jamjoum et al. Their identification of the transitions is confirmed and refined by spectrum simulations with total and partial densities of states from band structure calculations of Jaffe, Bendt, Zunger, and Bullett.New conduction-band maxima at energies not covered by the available calculations, are proposed and their consistency with the experimental loss energies is shown by another simulation with Lorentzian density peaks.