Recently i have synthesized SnO2 and cobalt/copper doped SnO2 nano particles. The PL spectrum shows a visible colored emission peak that is attributed to oxygen vacancy. The intensity becomes reduced in the case of doped samples when compared to undoped. Does this suggest a decrease in defect level in the system?
Furthermore, the conductivity shows good increment for undoped and first concentration of dopant in SnO2, Upon increasing concentration the conductivity is reduced when compared to undoped Sno2. What could be the reason for this?
In general, doping is induced to increase the conductivity, and if such suppression takes place, how should I justify the same to write my manuscript?
Mr P Baraneedhran, visible coloured emission in case of undoped SnO2 is surely due to generation of localised defect level in between VB and CB which reduces the band gap and hence red shifted emission is observed, but in case of doped sample you cannot conclude the supression of defect levels just because of PL quenching. Reduced PL intesity is due non-radiative collision between surrounding dopant ions. What was the dopant concentration (w.r.t SnO2) ? There is an optimum conc. limit for doping to increase the PL intensity, if you cross that level then you are bound to get reduced PL intensity.
I do not have much idea regarding conductivity and effect of dopant ion on conductivity of host. But may be the same kind of something is working in this case also (excluding non radiative transition)
One possible way we follow is to make the powder as pellet with uniform size and measure the conductivity. And the other is making them as a substrate
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