Mg Doping Effects on Optical and Electrical Properties of Solution-Processed ZnO Quantum Dots Based Thin Film Devices

The effects of Mg doping on the optical and electrical properties of solution-processed ZnO quantum dots (QDs) thin film has been analyzed. The thin film of ZnO QDs with different doping concentration of Mg (2% and 4%) are deposited over the glass substrate using solution processing. The effect of doping is evident on the bandgap of the material as the doped QDs shows blue shift in the absorption spectrum. Further, we have analyzed fabricated device of Mg-doped ZnO QD and calculated carrier concentration, Hall mobility, and sheet resistance. The values found to be 4.88x1014 cm-3, 4.92 cm2/VS, and 5.18x108 Ω/□ respectively for Mg (2%)-doped ZnO QDs and 5.39x1014 cm-3, 6.60 cm2/VS, and 5.56x108 Ω/□ respectively for Mg(4%)-doped ZnO QDs. The device with doping of 4% Mg shows the better electrical properties comparative to ZnO QDs with Mg doping of 2% and 0%. The transmittance curve of ZnO QDs shows the sharp cut-off for visible region with increase in doping percentage and Mg(4%)-doped ZnO shows ~90% transmittance across the visible region with sharp increase in 360nm. These characteristics of Mg-doped ZnO can be further utilized for photodetection application of short wavelengths.