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End date: 1999Subject: search.filters.subject.Surface states

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    Electrolyte electroreflectance study of surface optimization of n-CuInSeâ in photoelectrochemical solar cells
    (Journal of Electrochemical Society, 1986) Shen, Wu-Main; Siripala W; Tomkiewicz, M.; Cahen, D.
    Electrolyte electroreflectance is used to show that the main effect of Br2/MeOH etching of CuInSe2 is to remove the pinning of the Fermi level, which is due to a monolayer of states located 0.17V positive to the potential of CuInSe2 the solution. The flatband potential of in polysulfide solution was found to be ?0.62V vs. the solution potential, while in polyiodide solution it is shifted to ?0.70V vs. the potential of that solution. This shift can explain some of the improvement in performance in polyiodide compared to polysulfide. The bandgap of CuInSe2 was found to be a direct transition at 1.01 eV with a three?dimensional critical point.
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    Interactions Between Photoinduced and Dark Charge Transfer across n-TiO[sub 2]Aqueous Electrolyte Interface
    (Journal of Electrochemical Society, 1982) Siripala W; Tomkiewicz M
    An intermediate of the dark reductive reaction of with an aqueous electrolyte was identified. This intermediate forms surface states on the semiconductor. The energy and surface concentration of these states were evaluated by impedance measurements. We report on sub?bandgap photoresponse due to excitation of electrons from the valence band to these states. The potential?photocurrent behavior of these states is unique and is being fully accounted for by the proposed mechanism of their dynamic formation and annihilation.
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    Direct Observation of Surface States at the TiO2 Electrolyte Interface
    (Journal of Electrochemical Society, 1981) Siripala W; Tomkiewicz M
    Relaxation Spectrum Analysis was suggested as a general technique for mearsurements of charge accumulation modes and their corresponding relaxation times at the space charge layer of a semiconductor with strong emphasis on semiconductor liquid junction interfaces. Among all the reported results(2-4),none was, as yet, confirmed by an independent technique.
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    Observation of Intrinsic Surface States at the TiO2 Aqueous-Electrolyte Interface by Sub Band-Gap Electroreflectance Spectroscopy
    (Physical Review Letters, 1983) Siripala W; Tomkiewicz M
    Surface states were detected with sub?band-gap electroreflectance spectroscopy in the presence of electrolytes that can adsorb on the surface of TiO2. The energy of these states is located 1.3 eV below the conduction band and they can be detected only in the weak accumulation mode. The potential distribution at the interface as a function of the electrolyte was investigated by impedance spectroscopy. These results were interpreted in terms of "intrinsic" surface states of the unsolvated surface.