Semiconductor calcium semi-silicide (Ca₂Si) with a complex crystal and energy band structure is theoretically characterized by a direct fundamental transition, which is difficult to identify experimentally in Ca₂Si films due to high absorption at defect levels. The study of the temperature dependences of photoconductivity in Ca₂Si epitaxial films is one of the methods for assessing both the nature of the fundamental transition and a number of thermodynamic parameters. In this work, photoconductivity was firstly observed in an epitaxial Ca₂Si film grown on a Si(111) substrate in the temperature range from 10 K to 300 K. Based on an analysis of the parameters of three thermodynamic models, the existence of a direct fundamental transition E_g = 1.195 eV at 0 K was proved, and the effective phonon energy (<E_ph>), the Einstein (Ξ) and Debye (Θ_D) temperatures, as well as the electron-phonon coupling constant, and the hole mobility were determined.