Photoluminescence properties of polycrystalline AgGaTe 2

Abstract

Abstract Due to its high absorption coefficient and close to optimal bandgap energy, AgGaTe 2 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 AgGaTe 2 . 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 (1.337 eV), the band-to-tail (1.317 eV) 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.