Electron paramagnetic resonance and photoluminescence study of defects in CuGaSe2 single crystals grown by the traveling heater method

Electron paramagnetic resonance (EPR) at T = 4.2 K and photoluminescence (PL) spectra at T = 20 K have been employed to elucidate point defect features in CuGaSe2 crystals grown by the traveling heater method. Isotropic and anisotropic paramagnetic centers have been found in crystals as-grown and annealed in various gas mediums. Three PL bands have been observed and the influence of H-2, O-2 and Se-2 annealing has been studied. The presence of donor singlet V-se(+) has been evidenced in as-grown and H-2 annealed crystals. Complex study of EPR, PL spectra and defect physics models have allowed the addition of the point defect ensemble in CuGaSe2 with defect pairs (2V(cu)(-) + Ga-cu(2+)). V-cu and other defect complexes, according to treatments used in this work.