Tungsten oxide, single crystals

Molybdenum(IV) Oxide and Tungsten(IV) Oxide Single Crystals 149... 

MOLYBDENUM(IV) OXIDE AND TUNGSTEN(IV) OXIDE SINGLE CRYSTALS... 

The silicon detectors were made of n-typed single crystal of 1 mm thick. They have a MOS structure of gold, tungsten oxide, n-typed silicon and aluminum back contact. Since these layers can be deposited on the silicon wafer by evaporation techniques, the fabrication process is so simple as to be applicable to fabrication of the detectors for a special use. No surface treatment for passivation is given to them so that their performance is affected by ambient gases. For example, some good detectors show a leakage current of half micro-ampere at room temperature in the atmosphere, but a few micro-ampere in vacuum. So, in order to stabilize their performance, the silicon detectors were operated at the dry ice temterature. 

The preparation of clean surfaces in uhv has become by now a standard procedure. Several texts deal with this problem [see for example Refs. (21) and (22)]. Single crystal surfaces are generally cleaned by chemical means (e.g. oxidation and subsequent flashing in the case of tungsten) or by argon ion sputtering (23) or by a combination of both (24). 

Anodic oxidation of metallic tungsten in methanol afforded a mixture of [W(OMe)s] and [WO(OMe)4]. After purification and treatment with MeOC2H4OH, crystals of [ LiW02(0C2H40-Me)3 2-2Li(IIOC2I I40Me)2][W60 9] were obtained.42 Single crystals of W(OMe)6 were also prepared by anodic oxidation and subsequent separation from by-product, [WO(OMe)4].43... 

Oxides, Reviews discussing the stoicheiometry, structures, and properties of tungsten oxides have been published. The production of M0O2 WOj crystals by vapour-phase chemical transport has been described and the Raman spectrum of single crystals of MoOj determined, at temperatures between 77 and 500 K, and shown to be very similar to that of monoclinic The reduction of and by Hj at elevated tempera-... 

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