Ag Chalcogenides

The high-temperature superionic properties of the Ag + and Cu + chalcogenides (of general formula A2X, with A = Ag, Cu and X=S, Se, Te) have been extensively studied. These compounds provide an interesting comparison with their halide counterparts, particularly when probing the effects of the doubled cation density on the ionic diffusion mechanisms and macroscopic ionic conductivity [37]. 

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The relief masks formed from the photoresists have very high resistance in oxygen plasma. This enables a use of the Ag/chalcogenide layer as a top layer in bilayer photoresists with high resolution and aspect ratio. The under layer of the photoresist is usually made of polymer such as polyimide. 

Fig. 1. Chalcogenide halides in ternary systems having the components the Group IB elements Cu, Ag, and Au, the chalcogens S, Se, and Te, and the halogens Cl, Br, and I, They are indicated as M , Y, and X ", respectively. (Redrawn from A. Rabenau, H. Rau, and G. Rosenstein, J. Less-Common Metals 21, 395 (1970), Fig. 4, p. 401.)...

CsFeo.72Agi.28Te2,1053 and Cs2Ag2ZrTe4. The latter has a structure that comprises 2D slabs of Ag- and Zr-centered tetrahedral separated by Cs+ cations.1054 Gas-phase silver chalcogenide ions of the type [Ag2 i E ] (E = S, Se, Te) with < 14 have been investigated by laser-ablation Fourier transform ion cyclotron resonance mass spectrometry.1055... 

Solution pH is an important variable, as it controls solubility, the deposition potential, and precursor speciation [140], As noted, one of the advantages of using an ALE process is that very different solutions can be used for each step in the cycle. For instance, pH 4 Cd solutions have been used with pH 10 Te solutions to form CdTe. Some care must be taken rinsing between solutions, however. On the other hand, Foresti et al. have used the same pH for both the metal and chalcogenide in the formation of II-VI compounds, such as CdS and CdSe on Ag single crystals [115, 116, 123, 143], To keep the Cd from precipitating in the basic solution, they complexed it with pyrophosphate. 

Photoirradiation of this stacked film causes the Ag to diffuse into the Se-Ge film in a process referred to as Ag-photodoping. This diffusion, which is characteristic of amorphous chalcogenide materials, causes the Se-Ge film to become insoluble in alkaline solutions and the resist thus functions as a negative-type photoresist. The photodoped regions also are resistant to fluorine-based plasmas enabling dry development of the resist (7). Dry development has also been achieved using a reactive-ion etching (RIE) technique and is discussed later. 

The R-M-Z-X (M = Cu, Ag Z = Si, Ge, Sn, X = S, Se) systems have been investigated mainly across the R2X3-M2X-ZX2 sections. No quaternary compounds are known for Te systems. Quaternary compoimds that form in these systems are listed in Table 38. Among all of these 105 quaternary chalcogenides only four compoimds crystallize in SG other than P63. In several series of the silver compounds, occupational disorder for the silver atom has been foimd. 

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