ESR and PL characterization of point defects in CuGaSe2 single crystals

Electron spin resonance (ESR) and photoluminescence (PL) spectra were employed to elucidate point defect features in CuGaSe2 crystals grown by the traveling heater method. The isotropic paramagnetic center has been found in the crystals as-grown and annealed in various gas mediums. The PL bands have been observed in dependence on H2-, O2- and Se2-annealings. The presence of donor singlet VSe+ has been evidenced in the as-grown and H2-annealed crystals. The ESR, PL data and appropriate models allow to add the point defect ensemble in CuGaSe2 with other complex defects accordingly the treatments used in this work.