Luminescent and Photoconductive Properties of AgGa2.5In2.5S8 and CuGa2.5In2.5S8 New Semiconductors

Abstract

Results of a complex study of photoluminescence (PL), photoconductivity (PC) and photo-voltaic (PV) spectra in AgGa2.5In2.5S8 and CuGa2.5In2.5S8 single crystals are presented. The values of indirect (Egi=2.25 eV) and direct (Egd=2.60 eV, T=300 K) gaps in AgGa2.5In2.5S8 have been determined. PL spectrum of AgGa2.5In2.5S8 is shown to consist of two overlapping bands with the maxima at 1.57 and 1.95 eV (T=77 K), while CuGa2.5In2.5S8 is characterized by a single PL band, the position of its maximum (1.72–1.77 eV) depending upon the excitation power density. The radiative electron transitions in CuGa2.5In2.5S8 are assumed to occur from the quasicontinuously distributed traps below the bottom of the conduction band to an acceptor level with 0.07 eV activation energy.