Analytical characterization of CuInS 2 semiconductor material

Abstract

Systematic analytical procedures have been developed for determination of the stoichiometry of CuInS 2 and estimation of trace elements, including dopants and impurities, in the material. Samples of CuInS 2 are digested in an oxidizing acid to ensure completely transformation into Cu 2+, In 3+ and SO 4 2− ions. The stoichiometry determination is made sequentially by controlled potential electro-deposition of copper, followed by its EDTA titration, titrimetric determination of indium and gravimetric determination of sulphate, in a single sample solution. The relative errors for the determination of Cu and In are found to be −0.08% and +0.11% respectively, fulfilling the requirement for accurate stoichiometry assessment; that for S is −0.66%, which though rather high is still acceptable. For the determination of trace elements in CuInS 2, multistage combined procedures are employed. Cu in the sample solution is removed by electro-deposition and In by extraction of HInBr 4 with isopropyl ether, then most of the trace elements are finally determined by atomic-absorption spectrometry, and the rest by neutron-activation analysis. All the steps involved in the procedures have been optimized by using radioisotopes as tracers. By the procedures developed, a wide range of trace elements in CuInS 2, down to submicrogram level, can be determined.