Optoelectronic surface emitters of terahertz radiation from copper chalcogenides

Terahertz pulse generation at the surfaces of chalcopyrite I-III-VI₂ compounds prepared by several different technologies is presented and attempts to increase the emitted THz power by applying a reverse electrical bias to the surface structure are described. Three types of differently grown chalcopyrite samples were investigated. The largest terahertz pulse amplitudes were obtained when single crystalline CISe was used. Relatively strong THz emission was also observed from the surfaces of polycrystalline CISe and CIS layers. A significant enhancement of the amplitude by more than five times was achieved by applying an external bias to the surface of the CIS layer.