Abstract

Quantum dots (3–4 nm) of Zn1− x Cd x S (both free of Mn2+ and with Mn2+ incorporated) were synthesized through a novel solvothermal-microwave irradiation technique. Detailed structural analysis of the Zn1− x Cd x S and Zn1− x Cd x S:Mn2+ (x = 0, 0.25, 0.5, 0.75 and 1) materials was carried out using powder X-ray diffraction technique. For all the compositions, the crystallite size was controlled to less than 1.5 nm. The optical energy gap for Zn1− x Cd x S was found to vary from 3.878 to 2.519 eV and for Zn1−x Cd x S:Mn2+ it varies from 3.830 to 2.442 eV when x is increased from 0 to 1. Overall, the optical energy gap could be tuned from a minimum of 2.442 eV to a maximum of 3.878 eV. DC conductivity analysis (from 40°C to 150°C) and electrical energy gap analysis for all the compositions were also performed. The dc conductivity for Zn1− x Cd x S solid solutions varies from 0.3840 × 10−10 to 8.7782 × 10−10 mho/m at 150°C and for Zn1− x Cd x S:Mn2+ it varies from 0.5751 × 10−10 to 9.8078 × 10−10 mho /m at 150°C (for x = 0 to x = 1). The method of synthesis and the results observed in this investigation may assist in the fabrication of optical devices when the required operational performance falls under the range observed in the study.