Growth of conductive copper sulfide thin films by atomic layer deposition

Copper sulfide thin films were deposited on soda lime glass and Si( 100) substrates by atomic layer deposition (ALD) using the beta-diketonate-type volatile Cu compound Cu(thd)(2) (thd = 2,2,6,6-tetramethyl-3,5-heptanedione) and H2S as precursors. Depositions were carried out in the temperature range 125-250 degreesC. The film growth was surface-controlled in the temperature ranges 125-140 degreesC and 125-160 degreesC on glass and silicon substrates, respectively, growth rate being approximately 0.3 Angstrom cycle(-1) on both substrates for films of a thickness above approximately 50 nm. For thinner films the growth rate was higher, approximately 0.5 Angstrom cycle(-1). The deposited CuxS thin films were characterized by X-ray diffraction (XRD), time-of-flight elastic recoil detection analysis (TOF-ERDA), atomic force microscopy (AFM) and four-point resistivity measurements to determine crystallinity, chemical composition and surface morphology as well as surface resistivity (1x10(-4) Omega cm), respectively.