We have studied deep-level impurities in CdTe/CdS thin-film solar cells by capacitance–voltage (C–V), deep-level transient spectroscopy (DLTS), and optical DLTS (ODLTS). CdTe devices were grown by close-spaced sublimation. Using DLTS, a dominant electron trap and two hole traps were observed. These traps are designated as E1 at EC−0.28 eV, H1 at EV+0.34 eV, and H2 at EV+0.45 eV. The presence of the E1 and H1 trap levels was confirmed by ODLTS. The H1 trap level is due to Cu-induced substitutional defects. The E1 trap level is believed to be a deep donor and is attributed to the doubly ionized interstitial Cu or a Cu complex. The E1 trap is an effective recombination center and is a lifetime killer.

We have studied deep-level impurities in p+–n GaInNAs solar cells using deep-level transient spectroscopy (DLTS). These films were grown by atmospheric- and low-pressure metalorganic vapor-phase epitaxy. The base layer is doped with silicon, and the emitter layer is zinc doped. Two types of samples have been studied: samples were grown with and without the addition of oxygen impurity. Two electron traps were found in all samples. These are designated as: E1, at EC−0.23–EC−0.27 eV, E2 at EC−0.45 eV, and E2* at 0.77 eV. With the addition of oxygen impurity, DLTS showed additional traps designated as E3 (electron) at EC−0.59 eV and H3 (hole) at EV+0.59 eV. Using secondary ion mass spectroscopy, the oxygen concentration was found to be about 2–3×1019 and 1×1017 cm−3 in two sets of samples. However, only samples containing oxygen contained the two near-midgap levels (E3 and H3). We present evidence that these levels are associated with the oxygen defect. As we change the dc bias voltage, the E3 trap disappears in unison with the appearance of the H3 trap. Furthermore, E3 and H3 trap levels have comparable capture cross sections. This oxygen-related trap is an effective recombination center. The measured Shockley–Hall–Read lifetime for this center is about 0.6 μs.

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Technologically the electrochemical deposition method through the influence of potential, temperature, pH and composition of reactants offers excellent control lover the properties of semiconductors Using a potentiostatic approach, the films of CdS were deposited on t i n oxide coated glass substrates at merent conditions. The films were found to be smooth, uniform and adherent 114th a small grain size. X-ray &tion analysis indicated a hexagonal phase rather than the cubic phase.Electrochemica1 deposition parameters were studied to