Luminescence and impurity states in CuInSe2

The photoluminescence spectrum of melt-grown n-CuInSe2 single crystal at 7 K, has been determined near the fundamental absorption edge. Three peaks, at approximately 0.980, 0.990, and 1.013 eV, have been observed. Considering the transition probabilities of recombination processes, donor-to-acceptor pair and the corresponding free-to-bound transitions have been identified. From the data, an absorption edge at (1.023±0.003) eV, a donor state at (10±2) meV, and an acceptor state at (33±2) meV have been determined.