I have synthesized magnesium oxide (MgO) thin film by spray pyrolysis method by varying the concentration of Mg (0.05, 0.1, 0.15 and 0.2 mol/l). the transmission spectra below shown a value more than 100% in the wavelength region 300 -500 nm. The UV Vis spectrophotometre used to measured the optical transmission and reflection of type Perkin Elmer Lamda 950. I would mentioned that I have done the baseline correction before doing measurement and this findings only obtained for MgO compound.
In most of cases, these types of problems occured due to incorrect baseline. I think you should do the baseline again. Also, check the procedure of baseline as it depends on the type of instrument used.
Another possible reason is the fault in detector. You can check it by characterizing your samples in another instrument or by changing detector.
Dear Maher Tlili
This phenomenon can occur in ultrawide-bandgap thin films which have an absorption edge less than or equal to that of the substrate (glass), for example ZrO2, MgO, Ga2O3, etc..., thus this problem can be avoided during characterization by deposition of these films On a quartz substrate to avoid error .
The optical properties of these films deposited on glass substrates can also be measured using reflectance or ellipsometer.
Best regards,
O.Ben Khetta
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