CU(1-Y)AGYINS2(1-X)SE2X AS A PROTOTYPE OF THE PENTENARY CHALCOPYRITE SEMICONDUCTOR SYSTEM FOR SOLAR PHOTO-VOLTAIC CELLS

Group III-V mixed alloy quarternary semiconductors, such as Ga(1-y)InyAs(1-x)Px, have been extensively employed in lattice matching different semiconductor layers (at specified bandgaps) to form heterojunction electro-optical devices. The feasibility of employing the analogous pentenary alloys, consisting of the ternary chalcopyrites groups I-III-VI2 and II-IV-V2, are being reported. As a prototype of such alloys, samples of the pentenary CU(1-y)AgyInS2(1-x)Se2x have been synthesized and studied. These were prepared by reacting stoichiometric powder mixtures at about 900°C. X-ray diffractometry tests suggest the compounds maintain complete solid solubility throughout the system in a chalcopyrite type crystal structure. The alloy's intrinsic conductivity type appears to tend towards n-type for silver and sulfer rich compounds, while forming p-type for copper and selenium rich materials. Using cathodoluminescence spectra the sample's bandgap energies were estimated at 300 and 77 K. These indicate that all the alloys synthesized were direct bandgap semiconductors. Using least square fits on the data, topological maps of the bandgap and lattice constants versus composition have been produced. © 1979.