Oxide halides, chalcogen compound

At present, it appears that one of the criteria for construction of an ECALE cycle for a compound is whether atomic layers of one of the compound s elements can be formed using an equilibrium analogous to Eq. (5) oxidative UPD. As indicated above, the elements that can be deposited using oxidative UPD are mostly nonmetals such as the halides, chalcogen-ides, and pnictides. 

The next five chapters deal with deposition of specific groups of semiconductors. In Chapter 4, II-VI Semiconductors, all the sulphides, selenides, and (what little there is on) tellurides of cadmium (most of the chapter), zinc (a substantial part), and mercury (a small part). (Oxides are left to a later chapter.) This chapter is, understandably, a large one, due mainly to the large amount of work carried out on CdS and to a lesser extent on CdSe. Chapter 5, PbS and PbSe, provides a separate forum for PbS and PbSe, which provided much of the focus for CD in earlier years. The remaining sulphides and selenides are covered in Chapter 6, Other Sulphides and Selenides. There are many of these compounds, thus, this is a correspondingly large chapter. Chapter 7, Oxides and Other Semiconductors, is devoted mainly to oxides and some hydroxides, as well as to miscellaneous semiconductors that have only been scantily studied (elemental selenium and silver halides). These previous chapters have been limited to binary semiconductors, made up of two elements (with the exception of elemental Se). Chapter 8, Ternary Semiconductors, extends this list to semiconductors composed of three elements, whether two different metals (most of the studies) or two different chalcogens. 

The compounds TlYX are insoluble in water and organic solvents. Decomposition with oxidizing acids and bases leads to segregation of the chalcogen. On heating, disintegration into T1(I) halide and chalco-gen takes place between 96 and 132°C (22). The decomposition is incomplete for the chlorides, which form TI4YCI4 321). The electric conductivity of TljS-TlCl melts has been measured 404). 

The chemistry of l-phospha-4-boracyclohexa-2,5-dienes has been further developed to include preparations of the less substituted derivative (44) and its 1-arsa analogue (45) which is formed as a 2 1 mixture with its dihydro counterpart (46) (Scheme 6). The chemistry of (5) includes its methanolysis to (47), its oxidation with chalcogens to phosphorus(V) compounds (48), and its conversion to F-methyl and ethyl derivatives (49) with potassium in DME followed by alkylation with alkyl halides. The. B-r-butyl derivative (50) is also available from the addition of the alkylithium, but attempts to prepare the corresponding 5-Me derivative were thwarted by the failure of the intermediate ate complex (51) to undergo demethoxylation <83JOM(250)33>. 

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