Tauc-plot scale and extrapolation effect on bandgap estimation from UV–vis–NIR data – A case study of β-Ga2O3

• Published in: Journal of solid state chemistry 2020-10, Vol.290, p.121576, Article 121576
• Main Authors: Jubu, P.R., Yam, F.K., Igba, V.M., Beh, K.P.
• Format: Article
• Language: English
• Subjects: Bandgap; Extrapolation; Gallium oxide; Tauc plot; UV–vis–NIR
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2020.121576

The effect of the Tauc plot scale and bandgap extrapolation technique on estimated optical bandgap values is often not strongly emphasized. Herein, we demonstrate that the scale of the conventional Tauc plot and the extrapolation technique poses significant influence on the determined value of bandgap. The nanomaterial used for this study was prepared by the CVD method using different H2 reducing gas flow rates. XRD measurements confirmed polycrystalline β-Ga2O3 with high crystalline quality. FE-SEM analysis revealed nanohump-like morphology. UV–vis–NIR measurements generally showed increasing bandgap with rising H2 supply into the horizontal reactor. Specifically, it was observed that the proper extrapolation technique for bandgap estimation is more appropriate as compared to the values obtained from the traditional direct extrapolation method. It is established that direct extrapolation technique has the potential to either under - or over-estimate bandgap values, whereas the proper extrapolation method is promising for more reasonable values of optical energy gap. [Display omitted] •In depth discussion of β-Ga2O3 bandgaps derived using different Tauc plot scales and extrapolation techniques.•β-Ga2O3 has been synthesized by the CVD method.•The β-Ga2O3 films showed dense array of nanochump-like morphology.•The crystalline quality improved with rising H2 flow rate.•Bandgap increased with rising H2 supply into the horizontal reactor.