Terahertz radiation from nonstoichiometric CuInSe2 films excited by femtosecond laser pulses.

We report on the observation of efficient terahertz radiation from the surface of CuInSe₂ excited by femtosecond laser pulses. Terahertz radiation emitted by polycrystalline CuInSe₂ layers manufactured by using electrodeposition technology was as powerful as the signals radiated by single-crystalline semiconductor surfaces. It has been found that terahertz radiation efficiency is critically dependent on the stoichiometry of the CuInSe₂ layers. The results of a double-pulse excitation experiment have indicated that terahertz radiation from the photoexcited surfaces of CuInSe₂ samples was caused by the presence of a built-in electrical field at those surfaces. [ABSTRACT FROM AUTHOR]