A Controlled Growth Process To Design Relatively Larger Size Semiconductor Nanocrystals
journal contributionposted on 17.01.2013, 00:00 by Santanu Jana, Bhupendra B. Srivastava, Narayan Pradhan
The growth of semiconductor nanocrystals in solution is mostly governed by the kinetic and thermal modes of control of the reaction process. In most of the cases, the size of the particles is limited within 5–6 nm, and further annealing mostly defocuses the particles size distribution. But, herein, we report a self-driven growth protocol which supplies the monomer continuously to significant extent and delays the thermal diffusion-controlled ripening process. This has been achieved by choosing appropriate sulfur precursor in the synthesis of metal sulfide nanocrystals which controls the sulfide ion concentration in the reaction medium via establishing an appropriate chemical equilibrium. As a consequence, the monomer concentration retains above their critical limit and it delays the ripening process. Finally, the nanocrystals can grow even larger than 10 nm, which are difficult to obtain from different established synthetic approaches. This has been observed for several semiconductor nanocrystals such as ZnS, CdS, CdZnS, and also in ZnSe nanocrystals. Further, this growth process has been adopted to dope Mn in larger sized ZnS and CdZnS nanocrystals, and efficient dopant emission has been obtained.