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The defect and band edge related signals in the optical spectra for Ga-doped ZnO thin film were described using a piezoelectric photothermal (PPT) spectroscopy. The PPT peak of 2.5eV was observed for undoped ZnO grown under a low oxygen flow rate (OFR) while Ga-doped samples did not show any peak, indicating that Ga doping inhibits the generation of the oxygen vacancies.

AgInS2 crystals have been grown at below melting point by using a Hot-Press method. The samples grown at 400∼600 °C under 10 MPa pressure were found to contain AgIn5S8. Occurrence of this phase decreased with increasing growth temperatures and at 700 °C a sample containing only the AgInS2 phase was successfully obtained. Furthermore, the elemental compositions were found to become increasingly stoichiometric with increasing temperature. We also found that conduction type could be changed from n to p-type by Sb-doping, perhaps as a result of the substitution defect of Sb atoms on the S site. [Copyright &y& Elsevier]

Abstract: Structural electrical and optical properties of AgInS2 (AIS) thin films grown by the single-source thermal evaporation method were studied. The X-ray diffraction spectra indicated that the AIS single phase was successful grown by annealing above 400°C in air. The AIS grain sizes became large with increasing the annealing temperatures. All polycrystalline AIS thin films were sulfur-poor from the electron probe microanalysis and indicated n-type conduction by the Van der Pauw technique. It was deduced that the sulfur vacancies were dominant in the films and enhanced n-type conduction. [Copyright &y& Elsevier]