In situ and ex situ characterization of (Ag, Cu)InSe2 thin films

In situ and ex situ characterization methods have been used in order to investigate the growth as well as the physical and chemical properties of (Ag, Cu)InSe₂ (AgCIS) thin films deposited by direct current (dc) magnetron sputtering. Data acquired by real time spectroscopic ellipsometry (RTSE) were used to extract growth parameters such as thickness and surface roughness. A study of the growth parameters revealed that the layers demonstrated Volmer-Weber growth behavior. The complex dielectric functions, (ϵ₁ ϵ₂), of AgCIS at high and room temperatures as a function of x = Cu/(Ag+Cu) were also extracted from the RTSE data. The band gaps were extracted from the RTSE dielectric functions and compared with ex situ measurements.