Gallium oxide electrodes

A certain relationship, which exists between the bulk and surface properties of semiconducting materials and their electrochemical behavior, enables, in principle, electrochemical measurements to be used to characterize these materials. Since 1960, when Dewald was the first to determine the donor concentration in a zinc oxide electrode using Mott-Schottky plots, differential capacity measurements have frequently been used for this purpose in several materials. If possible sources of errors that were discussed in Section III.3 are taken into account correctly, the capacity method enables one to determine the distribution of the doping impurity concentration over the surface" and, in combination with the layer-by-layer etching method, also into the specimen depth. The impurity concentration profile can be constructed by this method. It has recently been developed in greatest detail as applied to gallium arsenide crystals and multilayer structures. 

Reactivity of LaGaOs with electrode materials has also been investigated [81,82]. Platinum seems to be easily reacted with gallium oxide to reduce Ga " " to Ga " which is volatile. As for the stability of LaGaOs-based electrolyte under... 

A liquid gallium electrode has similar properties to the mercury electrode (at temperatures above 29°C), but it has a far greater tendency to form surface oxides. 

A different type of ECL can be observed at certain oxide-covered metal electrodes such as aluminum, tantalum, magnesium, gallium, or indium, during the persulfate, oxygen, or hydrogen peroxide. However, the mechanism is... 

Substrates, Films are usually prepared on platinum or gold electrodes which are inert, but semiconducting materials including indium tin oxide, n-type polycrystalline silicon, gallium arsenide, cadmium sulphide and cadmium selenide, graphite [38, 59], and oxide covered metals [60] have also been used. In the majority of cases, the films are produced readily and the only serious limitations are the potential and the nucleophilic nature of the solution. 

Apart from metals, good-quality polypyrrole films have also been prepared using a variety of semiconducting materials, such as indium-tin oxide (ITO) glass [39,40], gallium phosphide [41], silicon [42-44], cadmium sulfide, or cadmium selenide [45] as the electrode. 

New developments relating to the manufacture of thin film transistors (TFT) are being reported from Japan where the Tokyo Institute of Technology has developed a flexible, transparent device on a PETP substrate. This TFT comprises an amorphous oxide semiconductor, which serves as the active layer, and which is made from indium, gallium and zinc oxide deposited by laser ablation to a thickness of 30-60 nm. The TFT, with its transparent electrodes and circuitry, is manufactured in a vacuum at a temperature of 150 "C or less. Because of this low processing temperature it is possible to use low cost PET film, with a thickness of 200 pm, as a substrate thereby enabling transistors to be manufactured at a relatively low cost. 

Students construct an electrochemical cell with a nickel wire cathode and a copper plate as the anode. One side of an aluminum oxide filter with 20 nm diameter channels is exposed to a nickel plating solution when attached to the copper electrode. Gallium-indium eutectic paint is applied to the other side of the filter in order to maintain electrical contact with the electrode. Students connect the electrodes to a 1.5 V battery for approximately 30 minutes as the nickel cations are reduced to nickel metal within the filter pores. Nickel nanowires grow at a rate of approximately 1 micrometer per minute. 

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