Development of an algorithm for precise and automated determination of optical band gap from Tauc analysis: case studies using alpha-irradiated CR-39 detectors

Abstract

Tauc analysis is popularly used for the determination of optical band gap by extrapolating the linear portion of the Tauc’s plot and finding its intersection point at energy axis. In most of the studies, the data points in the linear portion of the Tauc’s plot are selected manually, which is time-consuming and the reproducibility in the selection process gets affected. To overcome this, an automated determination of band gap has been proposed for ensuring the reproducibility as well as for faster selection process. In this work, we report the development of an efficient algorithm which can provide the information of the optical band gap by Tauc analysis. The algorithm is based on finding the linear portion around maximum slope of the Tauc’s plot. A computer program (autoTauc) based on the algorithm was written and was validated through CR-39 irradiated to four different alpha fluences. The extrapolated linear line obtained through linear regression (using the program) was observed to pass through the linear portion of the Tauc’s plot. The optical band gap was found to be decreasing linearly with the alpha fluence for both direct and indirect transitions. Also the direct band gap was found to be higher than the indirect band gap.