Photoluminescence properties of polycrystalline AgGaTe2

Due to its high a,)sorption coefficient and close to optimal bandgap energy, AgGaTe2 is a promising material for solar energy conversion. In order to avoid recombination losses, the study of the defect structure of solar cell materials is very important. This paper reports the results of photoluminescence experiments on polycrystalline AgGaTe2. Two emission regions centred at 1.32 and 0.8 eV were found. The first region appears near the bandgap energy and comprises three bands that are identified by the theory of heavily doped semiconductors as the band-to-band (1.337eV), the band-to-tail (1.317eV) and the band-to-impurity (1.287 eV) recombination. The second deep PL region consists of two bands with the peak energies of 0.835 and 0.75 eV. Both these deep bands have rather low thermal activation energy; 18.5 and 20.8 meV, respectively. The possible origins of these bands are discussed. (c) 2006 Elsevier B.V. All rights reserved.