Study of point defects in CuGaSe2 single crystals by means of electron paramagnetic resonance and photoluminescence

Point defects in CuGaSe2 single crystals as vacancies VSe, VCu and defect pair (2VCu−+GaCu2+) have been studied by means of electron paramagnetic resonance (EPR) and low-temperature photoluminescence (PL). EPR hyperfine structure has been found at temperatures as low as 1.45–45 K and the temperature dependence of EPR line is discussed. Photo-EPR spectrum reveals optically active behavior of intrinsic point defects in CuGaSe2 crystals. Three bands of PL emission show different origins and two low-energy bands at 1.55 and 1.58 eV have been found to be steady despite H2-, O2- and Se2-annealings. The experimental data added with electric characterization in accordance with the used annealings and together with a defect physics model allow consideration of the point defect ensemble in CuGaSe2 in more detail.