EFFECT OF PREPARATION CONDITIONS ON THE OPTOELECTRICAL AND STRUCTURAL PROPERTIES OF CuInS_2 THIN FILMS GROWN BY A TWO-STEP PROCESS

摘要

CuInS_2 thin films were prepared on soda-lime glass substrates by a two-step process using elemental sulfur evaporated froman effusion cell and metallic precursors evaporated from tungsten boats. The films were characterized by spectraltransmittance, conductivity, thermoelectric power and x-ray diffraction (XRD) measurements to investigate the effect of thegrowth temperature on the optical constants (refractive index n, absorption coefficient a and optical gap E_g), crystallographicphase and electrical transport properties.The optical constants and the crystallographic parameters of the CuInS_2 films were calculated using transmittance, XRDmeasurements and computational tools to simulate the transmittance and XRD spectra, respectively. The results showed thepresence of secondary In_2Se_3 and Cu_2S phases in some CuInS_2 films. However, it was possible to grow films containing onlythe CuInSe_2 phase by selecting adequately the preparation parameters. Furthermore, it was also found that the substratetemperature significantly affects the optical and electrical properties.