Assessing Tauc Plot Slope Quantification: ZnO Thin Films as a Model System

Jennifer B. Coulter, Dunbar P Birnie

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

One of the most frequently used methods for characterizing thin films is UV–Vis absorption. The near-edge region can be fitted to a simple expression where the intercept gives the band gap and the fitting exponent identifies the electronic transition as direct or indirect. [See Tauc et al., Physica Status Solidi 15, 627 (1966); naturally, these are usually called “Tauc” plots.] In earlier work, we found that direct band gaps fitted using Tauc's method can be quite accurate, to ∼1% [see Viezbicke et al., Phys. Status Solidi B 252, 1700 (2015)]. Still, slopes of these Tauc plots are less frequently quantified, even though the slopes are directly rooted in key band-structure parameters. In this study, we examine the reproducibility of Tauc plot slopes for ZnO as a model direct-gap material and compare these experimental values with the theoretically derived slope. In contrast to the band gap accuracy, the experimental slope values varied by several orders of magnitude. The histogram of slope values was significantly more compact for Tauc plots exhibiting less Urbach tail contribution. In these cases, the Tauc slopes can provide an order-of-magnitude quantification of other key band characteristics such as carrier effective mass.

Original languageEnglish
Article number1700393
JournalPhysica Status Solidi (B) Basic Research
Volume255
Issue number3
DOIs
Publication statusPublished - Mar 1 2018

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Energy gap
plots
slopes
Thin films
thin films
Band structure
histograms
exponents
electronics

Keywords

  • band gaps
  • near-edge absorptivity ratio
  • optical absorption
  • Tauc plots
  • thin films
  • ZnO

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Assessing Tauc Plot Slope Quantification : ZnO Thin Films as a Model System. / Coulter, Jennifer B.; Birnie, Dunbar P.

In: Physica Status Solidi (B) Basic Research, Vol. 255, No. 3, 1700393, 01.03.2018.

Research output: Contribution to journalArticle

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