Determination of the refractive index of tin telluride film using Terahertz spectroscopy

Tin telluride films were prepared and characterized using terahertz time domain spectroscopy. The films were deposited on glass substrate at different temperatures inside a vacuum chamber with a pressure of 10 -6 torr,\. The substrate temperatures were 30 degrees Centigrade and 50 degrees Centigrade approximately. The real and imaginary parts of the complex refractive index were determined using the transmission spectra. The complex refractive indices were plotted against frequency that ranged from 0 THz to 0.6 THz. For films deposited at 30 degrees centigrade, the real and imaginary parts of the refractive index were found to be 4.8 and 3.5 respectively. Those deposited at 50 degrees centigrade yielded values of 5.6 and 4.0 the real and imaginary parts of the refractive index was observed on both samples at about 0.5 THz. The imaginary part of the index decreased and an increase in the real part of the refractive index was exhibited. This behavior was attributed to the increase in the materials resistivity that slows down the propagation of the electromagnetic pulse. Negative imaginary part was obtained at about 0.5 THz, which indicated the onset of compression of the electromagnetic pulse at it penetrated the sample