Etude sur les défauts chimiques profonds dans le composé CuInSe2

Abstract

In this work, high quality CuInSe2 single crystals, grown by the vertical Bridgman technique are characterized by three measurement techniques: Deep Levels Transient Spectroscopy (DLTS), Minority Carrier Transient Spectroscopy (MCTS) and photoacoustic spectroscopy (PAS). Crystalline ingots of CuInSe2 were grown. The chalcopyrite structure of their powder was verified by X-ray. The optical absorption properties of the samples used were analyzed in the photon energy range from 0.6 to 1.3 eV from measurements made at room temperature using the photoacoustic spectroscopy technique. Then, Schottky aluminum contacts were deposited on the p-type materials in an evaporation system for the DLTS and MCTS analysis. Analysis of the extracted absorption coefficient spectral dependence from photoacoustic measurements showed that the bandgap energy of the samples is Eg = 1.017 eV, which is in close agreement with published data, and revealed the presence of not only two major shallow defect states, which are very near the valence band at h = 1.01 eV (L1) and h = 1.02 eV (L2), but also four deep defect levels having the activation energies of 270, 322, 333 and 344 meV corresponding, respectively, to the levels E4, E3, E2 and E1. DLTS measurements revealed the presence of three majority carrier traps in the samples with the activation energies 195, 378 and 526 meV. The first two levels compare well with photoacoustic detected levels. In the meantime, MCTS revealed the presence of one minority carrier trap was detected at 271 meV, which is good agreement to the one observed in photoacoustic measurements