Optical absorption study of ion beam synthesized polycrystalline semiconducting FeSi2

Abstract

Ion beam synthesized polycrystalline semiconducting FeSi2 on Si(001) has been investigated by transmission measurements at temperatures between 10 and 300 K. The existence of a minimum direct band gap was demonstrated and its variation with the temperature was studied by means of a three-parameter thermodynamic model and the Einstein model. Band tail states and states on a shallow impurity level were found to give rise to the absorption below the fundamental edge. The presence of an Urbach exponential edge was shown and the temperature dependence of the Urbach tail width was also studied based on the Einstein model. A strong structural disorder associated with grain boundaries between and within the FeSi2 grains and their related defects was found to be the dominant contribution at room temperature.

Study of optical absorption in TlGaSe2:Zn2+ single crystals

“…It has been shown both experimentally and theoretically that the exponential edge characterized by the Urbach rule can arise from both phonon dynamics and statistical structural disordering [25]. For high-quality crystalline semiconductors, the Urbach energy is directly linked with the temperature disorder, whereas for amorphous or heavily doped materials, it increases as a result of increasing statistical disorder.…”

Influence of cation substitution on phase transition and optical absorption edge in Cu6(P1-xAsx)S5I mixed crystals

“…3) by the Mahr equation [13]: (Table). E and U E are described within the framework of Einstein's model by equations [14,15]: and E U for all other Cu 6 (P 1-x As x )S 5 I mixed crystals are well described by the equations (4) and (5) Table. Fig . 5 shows the compositional dependences of the optical pseudogap * g E and Urbach energy E U for Cu 6 (P 1-x As x )S 5 I mixed crystals.…”

Electrical and optical parameters of Cu6PS5I-based thin films deposited using magnetron sputtering

“…It should be noted that, within the range of exponential behaviour of optical absorption for their spectral characterization, one can use the energy position of the exponential absorption edge Fig. 3 and can be described in the Einstein model by relations [15,16] ( ) is related to the intense motion of mobile copper ions participating in ion transport and is responsible for the ionic conductivity. The first term in the right-hand side of Eq.…”