Investigation of the propagation properties of terahertz waves through a semiconductor subwavelength slit

► We investigate the propagation properties of THz waves through InSb slits. ► Increasing the carrier concentration of InSb will decrease the propagation constants. ► Increasing the length of the filling materials will increase the effective indices. ► Increasing temperature will decrease the propagation constants of surface modes. ► Compared with the metal slits, the InSb slits show larger propagation constants.