In situ, real-time thickness measurement techniques for bath-deposited CdS thin films on Cu(In,Ga)Se2

A technique has been developed that can measure the thickness of a 30–70 nm thin film of cadmium sulfide on a Cu(In,Ga)Se2 substrate, in real time, as it grows in a chemical bath. The technique does not damage the film, and can be used to monitor batch depositions and roll-to-roll depositions with equal accuracy. The technique is based on reflectance spectroscopy through the chemical bath.

► Reflection spectra were collected during the chemical bath deposition of CdS.
► Two algorithms were generated to extract film thickness from each spectrum.
► Two conventional techniques were used to independently verify CdS film thicknesses.
► The accuracies of the algorithms are within 7% of the actual thicknesses.
► The algorithms offer in situ, real time thicknesses through the chemical bath.