E. I. LEONOV (c), V. M. ORLOV (c), V. A. CHALDYSHEV (b), and A. SILEIKA (a)The electroreflectance spectra of CdSnP, chalcopyrite single crystals have been investigated in the spectral region 1.0 to 4.7 eV at room temperature using polarized light. The electroreflectance structure in the region of the fundamental absorption edge and its polarization dependence are found to be in good agreement with the relative location of the valence bands earlier predicted theoretically. A great number of electroreflectance peaks has been observed in the spectral region 2.4 to 4.7 eV and interpreted by optical transitions at the I?, T, and N points of the Brillouin zone of the chalcopyrite lattice. The only transitions used were direct ones and responsible for the main structure in the optical spectra of sphalerite crystals. In addition, the fine structure of these optical transitions due to crystal field splitting has been included. npeHCTaBjIeHbI pe3yJIbTaTbI HCCJleAOBaHIIH CIIeIETpOB 3JIeHTPOOTPaHEeHHR MOHO-KpHCTaJIJIOB CdSnP, B IIOJIRpI130BaHHOM CBeTe B CIIeIFTpaJIbHOfi o6nac~H OT 1 ,o A 0 4,7 3B IIpH KOMHaTHOfi TeMIIepaType. CpTyHTypa CIIeKTpOB 3JIeKTpOOTpaHEeHIIR B o 6 n a c~~ OCHOBHOrO KpaR IIOrJIO~eHHR El ee IIOJIHpH3alJHOHHaR 3aBHCIIMOCTb IlOATBePAHJIU paHee TeOpeTHqeCKH IIpenCKa3aHHyIO CTPYKTYPY BaJleHTHOfi 30HbI. MHOHl eCTBO IIHHOB 3JIeHTpOOTpaHEeHUR B CIleHTpaJIbHOfi obnac~I1 OT 2,4 A0 4,7 3B XOpOluO HHTepIlpeTHpyeTCR OIITHqeCKUMH IIepeXOHaMH B TOqKaX r, T H N 3 0 H H EpHJIJIlO3Ha XaJlbKOIIUpHTa) 6blBIIIEIMH IlPRMbIMH H B C@aJIepHTe, IIpU YqeTe HX T O H H O~ CTPYICTYP~I BcneficTBm IipmTannmecKoro pacuenneHm, 0 6 y c n o~n e~-Horo ne@opMamiefi II HanmHeM HBYX COPTOB KaTHoHoB B pelue-me CdSnP,. 29

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The existence of a complete range of solid solutions between Bi12SiO20 and Bi12TiO20 is determined. The optical spectra: absorption in the vicinity of the fundamental edge, infrared absorption and reflection, and specific rotation of plane polarized light are studied for Bi12Si1−xTixO20 crystals. A continuous change of the optical spectra is observed, when the Bi12TiO20 content is increased. The linear dependence of some optical parameters on composition of Bi12Si1−xTixO20 crystals is determined.

The principal information of II--IV--V 2 compounds and their preparation in layer forro is summarized.The discovery that binary compounds of group III and V elements are semiconducting, with essentially the same diamond-like structure (covalent bonding, tetrahedral atomic arrangement) shown in purer form by group IV elementary conductors such as Ge and Si, soon led to the realization, in the mid-fifties, that justas these binary compounds can be considered formally as resulting from a heterovalent substitution of group IV elements by atoms of the adjacent IIIrd and Vth groups, there should also exist a group of ternary semiconducting compounds producable in similar fashion by the replacement of one of the atoms of a binary compound. Following confirmation of the existence of such ternary compounds, a respectable amount of work has been devoted to them, and especially to those of the II--IV--V~ type, in which the group III atoms of a III--V compound are substituted for group II and IV elements. Suffice it to say that the number of papers on II--IV--V 2 compounds now stands at more than 400 and is increasing progressively. (See, for example, bibliography [1] and review articles [2] and [3].)Yet despite the great interest they are believed to hold for semiconductor technology, deriving in part from their genetic relation to the III--V and group IV elementary semiconductors, in part from the properties they have been found to possess, ternary II--IV--V 2 systems are far less thoroughly investigated than these other materials and information on them is still relatively scarce. This and certain difficulties encountcred in their preparation have probably been responsible, in particular, for the rather limited progress made in exploring the possibility of obtaining ternary compounds in layers and films. At the same time, new trends in the semiconductor devices industry make us consider this problema matter of importance, and this has prompted us to attempt to summarize the principal information available on these compounds and their preparation in layer forin.