The results for iron oxide, thin film (∼500Å) electrodes, formed both by reactive sputtering from an iron target and by plasma oxidation of a sputter‐deposited iron film, are reported. The reactively sputtered electrodes were formed by deposition onto sputter‐deposited films of both iron and conducting indium tin oxide (ITO), while the plasma oxidized electrodes were formed with ITO only. The performance of the electrodes as photoanodes for
O2
evolution was found to be strongly dependent on a number of fabrication parameters, the best results being achieved for films formed on ITO and then vacuum annealed, both at 350°C. In this case, the performance matched or exceeded that reported in the literature for other methods of fabrication of polycrystalline iron oxide. Annealing these films in oxygen resulted in a decrease in photocurrent by a factor of three to four, as well as a 0.7 V suppression of the photocurrent onset potential. The effect was reversed on reannealing in vacuo. Postfabrication treatment of electrodes in various aqueous solutions was found to effect their performance significantly. More specifically, a substantial enhancement of the photocurrent in the onset region was achieved by treatment in a boiling KSCN solution. Mott‐Schottky plots and conductivity measurements are presented to illuminate these phenomena.
The photoelectrochemical properties of films of indium oxide formed in essentially three different ways are reported. These are (i) reactive sputtering of the oxide from an indium metal target, (it) thermal oxidation of thin indium metal films, also sputter deposited, and (iii) plasma oxidation of the same thickness of indium metal. While reactively sputtered films exhibit a maximum quantum efficiency -20% at 290 nm, similar to that achieved with single crystal In~O:~, the thermally oxidized films give -90% quantum efficiency at 310 nm. The bandgap energies as determined from photoelectrochemical studies were 2.8 eV (indirect) and 3.6 eV (direct) for all three types of films. The solid-state, optical, morphological, and photoelectrochemical properties of the three types of films are reported and compared. A major portion of the improvement of the thermally oxidized films over those reactively sputtered is morphological in nature, which suggests the possibility for substantial improvement of other photoelectrode materials utilizing the same effect.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.251.14.35 Downloaded on 2015-05-26 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.251.14.35 Downloaded on 2015-05-26 to IP
Durch Oxidation (O2, 30 min, 350°C) dünner In‐Metallfilme werden In2O3‐Filme von ca. 1000Å Dicke hergestellt und auf ihre photoelektrochemischen Eigenschaften untersucht.
We report the solid-state and photoelectrochemical properties of thermally grown and reactively sputtered In203 films of mean thickness <2000A grown on bare Pyrex, platinum, gold, and ITO. The colloidally rough, thermally grown films on bare Pyrex flats exhibited quantum efficiencies near unity at 310 nm, while the same thickness of uniformly flat In203 reactively sputtered directly onto Pyrex displayed no detectable photoresponse. Comparison of the morphological, solidstate, optical, and photoelectrochemical properties indicate that there are two sources contributing to the superior behavior of the colloidally rough films over the uniform flat films. The first is an improvement in the solid-state properties of the thermally grown films which gives rise to both a substantial increase in the majority carrier mobility and a much wider space charge region due to a reduced doping density. The second is purely geometrical in nature with the rough morphology leading to more minority carriers being generated near the semiconductor-electrolyte interface (roughness-enhanced transport) as well as to more light being absorbed in the rough films than in smooth films of the same mean thickness (roughness-enhanced absorption).) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 152.14.136.77
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