Dielectric functions and growth dynamics of CuIn1−x,GaxSe2 absorber layers via in situ real time spectroscopic ellipsometry

In situ, real time spectroscopic ellipsometry (RTSE) has been used to study the growth dynamics of the chalcopyrite thin film absorber layer; copper indium gallium diselenide, CuIn_1-x,Ga_xSe₂. Time dependent bulk layer (d_b) and surface roughness layer (d_s) thicknesses were extracted in the early stages of film growth using growth temperature optical dielectric functions determined in the same analysis. We find that an accurate determination of the dielectric function can be obtained during the initial stages of film growth where the surface roughness is relatively low. Non-destructive optical feedback via RTSE on the growth dynamics and electronic properties of the absorber layer could play an important role in improving device efficiencies on both the laboratory and industrial scales.