Preparation and properties of ternary II–IV–V2 layers and heterojunctions based on them

Abstract

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.

Synthesis of high-quality CdSiP2 polycrystalline materials directly from the constituent elements

“…The ampoule may crack due to the difference in thermal expansion between silica and cadmium phosphides. Thirdly, the dissociation of CdSiP 2 begins at about 400 1C [9]. Volatile substances can separate out of the ingot during cooling and the solidified melt always deviates from stoichiometric proportion.…”

“…It is hard to prepare it due to the high phosphorus pressure developed before complete synthesis and the high dissociation pressure at its melting point (22 atm) [2]. The growth of CdSiP 2 by halogen-assisted vapor transport and from molten tin solution has been reported by several authors [1,[8][9][10][11][12][13]. By reducing the formation temperature of CdSiP 2 , these methods keep synthesis process away from excessive pressure and prevent the explosion of silica ampoule.…”