Dominant UV emission and n-type conductivity in manganese doped Zinc Telluride quantum dots

Abstract

A dominant UV emission at 397 nm and an n-type conductivity in the manganese (Mn) doped Zinc Telluride (ZnTe) quantum dots (QDs) are reported in this article. Energy Dispersive X-ray analysis (EDAX) is used to confirm the composition of the undoped and Mn2+ doped ZnTe QDs. High Resolution Transmission Electron Microscopic (HRTEM) images depict the systematic and homogeneously distributed QDs. Selected Area Electron Diffraction (SAED) patterns exemplify the crystalline nature of the as synthesized QDs. From the X-ray Photoelectron Spectroscopic (XPS) analysis, Mn is found to be present in its divalent state of Mn2+. Tauc plots confirm the blue shift for the Mn2+ doped ZnTe QDs and the energy band gap is found to vary between 3 and 3.3 eV. The photoluminescence spectra in the red spectral region depicts the quenching effect when doped with Mn2+ and this may be attributed to the F-center like defects. The absence of the peak at about 525 nm wavelength (2.369 eV) indicates the suppressed Zn vacancy defects, in both undoped and Mn2+ doped ZnTe QDs. From the van der Pauw method of Hall measurements, Mn2+ doping in an n-type ZnTe QDs is found to increase the mobility and conductivity of the carriers than that is observed in the undoped ZnTe QDs. From the photoluminescence and van der Pauw Hall measurement studies, it can be said that Mn2+ is a worthy dopant for ZnTe QDs and can be used in the fabrication of p-n homo–junction diode.