ITO films as a functional material for THz radiation modulation

In this paper, we investigate the terahertz (THz) transmittance and band gap (BG) properties of magnetron sputtered indium tin oxide (ITO) thin films. The THz transmittance was measured using THz time domain spectroscopy, which provides insight into the interaction of terahertz radiation and free carriers inside the films. The band gap was determined from
spectrophotometric data using Tauc diagrams, which allowed the analysis of both direct and indirect electron transitions. The results showed that the THz transmittance decreases with increasing film thickness, primarily due to the increase in free carrier absorption associated with higher conductivity and carrier concentration in thicker films. The observed optical band gap values depend on the Burstein-Moss effect caused by the filling of low-energy states in the conduction band with free electrons. The obtained results demonstrate a close relationship between the electronic structure and terahertz response in ITO films, confirming their potential for efficient control of terahertz radiation and application in optoelectronic devices.