Nucleation, growth, and orientation analysis of quaternary-sputtered Cu(In, Ga)Se2

Cu(In, Ga)Se₂ films of various thicknesses were deposited from a single quaternary sputtering target and evaluated using x-ray diffraction and electron microscopy. Strong evidence of Volmer-Weber growth is observed, with the bare molybdenum bottom contact still observable after 600 seconds of growth and a nominal film thickness of ~100 nm. X-ray diffraction characterization reveals that the degree of preferred orientation increases with additional growth time, indicating film reorganization and preferential adherence of deposited species. Further, the degree of preferred orientation decreases with the age of the sputtering target, making this a possible technique to monitor the remaining target lifetime.