PbTe nanocrystal synthesis, chemical passivation and self-assembly into atomically coherent superstructures via oriented attachment

Abstract

Using oriented attachment two dimensional superstructures of PbTe quantum dots were synthesized. PbTe nanoparticles in the range of 4-5 nm were synthesized using the hot injection method. Due to the low stability of PbTe under ambient conditions the nanoparticles were treated using halogens. The higher stability under ambient condition makes them easier to use in future applications. This treatment helps in reducing the speed at which the particles oxidize and Bromide protects the particles against oxidation the best. The halogen treatment doesn’t hinder the particles during oriented attachment and appear to help synthesize larger structures due to the increased stability. Different superstructures were synthesized, ranging from honeycomb to linear and square structures. Square superstructures with patch sizes of about 200 nanometres can be synthesized with about 60% reproducibility. The square structures can be synthesized fairly reproducible but aren’t guaranteed, therefore increasing the reproducibility further could make further analysis of the structures, for example the electronic structure with STM, easier.