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 language | English |
|---|---|
| Article number | 1700393 |
| Journal | Physica Status Solidi (B) Basic Research |
| Volume | 255 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - Mar 1 2018 |
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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 journal › Article
}
TY - JOUR
T1 - Assessing Tauc Plot Slope Quantification
T2 - ZnO Thin Films as a Model System
AU - Coulter, Jennifer B.
AU - Birnie, Dunbar P
PY - 2018/3/1
Y1 - 2018/3/1
N2 - 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.
AB - 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.
KW - band gaps
KW - near-edge absorptivity ratio
KW - optical absorption
KW - Tauc plots
KW - thin films
KW - ZnO
UR - http://www.scopus.com/inward/record.url?scp=85043588400&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85043588400&partnerID=8YFLogxK
U2 - 10.1002/pssb.201700393
DO - 10.1002/pssb.201700393
M3 - Article
AN - SCOPUS:85043588400
VL - 255
JO - Physica Status Solidi (B): Basic Research
JF - Physica Status Solidi (B): Basic Research
SN - 0370-1972
IS - 3
M1 - 1700393
ER -