ELECTRICAL-PROPERTIES OF POLYCRYSTALLINE CHALCOPYRITE AGINS2 FILMS

Polycrystalline chalcopyrite AgInS2 films 2.0-3.5-mu-m thick have been formed on glass substrates. Resistivities, carrier concentrations, and Hall mobilities are measured at room temperature. These quantities are shown to be changed greatly by annealing under maximum S pressure for 1 h at different temperatures. Resistivities of 1-10(4)-OMEGA cm and carrier concentrations of 2 x 10(15)-3 x 10(20) cm-3 are obtained in n-type films. In p-type films, resistivities are found to be higher than 1 x 10(4)-OMEGA cm, and carrier concentrations are less than 3 x 10(15) cm-3. The effects of vacancies and interstitials of Ag, In, and S atoms are discussed to explain the observed changes in the electrical properties of the films. Owing to various structural imperfections, Hall mobilities are found to be less than 2 cm2/V s in both n- and p-type films. Au-p-type AgInS2 Schottky diodes have been fabricated. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics are measured at room temperature. The ideality factor is evaluated as about 1.63. In the frequency range 10(-4)-1 MHz, large frequency dispersion is observed in the C-V curves, and explained in terms of the response of deep defect levels.