Sputter deposition of CuInSe2 and CuGaSe₂ from composite targets on (100) Si

Thin films of CuInSe₂(CIS) and CuGaSe₂(CGS) were deposited on (100) Si substrates by RF magnetron sputtering using stoichiometric targets, at various substrate temperatures. Prior to film deposition, the Si substrates were cleaned using the RCA cleaning procedure and treated in a buffered oxide etch (BOE) solution. Deposited films were characterized using Rutherford backscattering spectroscopy (RBS), transmission electron microscopy (TEM) of cross-sectional samples and Hall measurements. Rutherford backscattering analysis indicated that the CIS films had a composition of Cu_0.8In_1.1Se_1.9, whereas CGS films were Cu-poor and Ga-rich with a composition of Cu_0.3Ga_1.5Se _1.5. Clean Cu-chalcopyrite/Si interfaces were obtained using BOE treated Si substrates. Transmission electron micrographs of cross-sectional samples indicated a polycrystalline film structure and that the native oxide on the Si substrate was eliminated. Energy dispersive X-ray spectroscopy (EDS) conducted in the TEM showed that contamination levels in the films were low. The Hall-mobility experiments performed the CIS film indicated that the material was of p-type conductivity with a carrier concentration of 9.6 × 10 ²⁰/cm³ and a Hall mobility of 390 cm²V ^-1s^-1.