Tauc plot
Encyclopedia
A Tauc plot is used to determine the optical gap, or Tauc gap, in amorphous thin film
materials. The Tauc gap is often used to characterize practical optical properties of amorphous materials.
A Tauc plot is a convenient way of displaying the optical absorption spectrum of a material pioneered by J. Tauc, who proved that momentum is not conserved even in a direct optical transition. Typically, a Tauc plot shows the quantity hν (the energy of the light) on the abscissa and the quantity (αhν)r on the ordinate, where α is the absorption coefficient of the material. The value of the exponent r denotes the nature of the transition; for example, r = ½ for indirect transitions. The resulting plot has a distinct linear regime which denotes the onset of absorption. Thus, extrapolating this linear region to the abscissa yields the energy of the optical band gap of the material. However, if the material in question does not have a single phase, it will likely not have a single distinct absorption onset, which corresponds to a more gradually-sloping curve in the Tauc plot. The figure below shows an example of a typical Tauc plot.
Thin film
A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin film construction....
materials. The Tauc gap is often used to characterize practical optical properties of amorphous materials.
A Tauc plot is a convenient way of displaying the optical absorption spectrum of a material pioneered by J. Tauc, who proved that momentum is not conserved even in a direct optical transition. Typically, a Tauc plot shows the quantity hν (the energy of the light) on the abscissa and the quantity (αhν)r on the ordinate, where α is the absorption coefficient of the material. The value of the exponent r denotes the nature of the transition; for example, r = ½ for indirect transitions. The resulting plot has a distinct linear regime which denotes the onset of absorption. Thus, extrapolating this linear region to the abscissa yields the energy of the optical band gap of the material. However, if the material in question does not have a single phase, it will likely not have a single distinct absorption onset, which corresponds to a more gradually-sloping curve in the Tauc plot. The figure below shows an example of a typical Tauc plot.