Energy spacing and sub-band modulation of Cu doped ZnSe quantum dots

Abstract

Cu doped ZnSe quantum dots (QDs) with various dopant concentrations were prepared using a growth doping technique to modulate their kinetics of Cu incorporation. Pre-synthesized ZnSe QDs with a low defect concentration and strong band-edge emission were fabricated under controlled reaction conditions, resulting from the low surface-to-volume ratio. The growth doping process was used to synthesize Cu doped ZnSe QDs and growth doping completed interior doping used Cu as a doping agent. The Cu doping overcomes the wavelength constraints of ZnSe QDs and enables elimination of the ZnSe host emission due to the formation of Cu states. Increasing the Cu dopant concentration to 0.4% resulted in an increase in the Cu-related emission intensity owing to the dominant recombination pathway which transfers to the Cu states, demonstrating the successful incorporation of Cu dopant atoms. The emission wavelength tuning of ZnSe QDs through Cu doping is clearly independent of the size variation, as evidenced by the ZnSe and Cu doped ZnSe QDs exhibiting similar nanoscale features. • Cu doped ZnSe quantum dots were fabricated using growth doping strategy. • Correlation between optical band gap and quantum dot size was investigated based on empirical approximation. • Formation of sub-bands states resulting from Cu incorporation achieves wavelength extension of ZnSe quantum dots. • Controlled doping level was limited due to passivating agents and formation of CuSe nanoparticles.