The Role of\nCounteranions in Solution Deposition of\nZnS Thin Films on GaAs

Using 5 commonly employed precursors for Zn<sup>2+</sup> cations,\nZnSO<sub>4</sub>, ZnI<sub>2</sub>, ZnCl<sub>2</sub>, Zn(NO<sub>3</sub>)<sub>2</sub>, and Zn(CH<sub>3</sub>COO)<sub>2</sub>, we demonstrate\nthe effect of counterions on ZnS thin film formation. We show that\nboth film nucleation and growth stages are strongly dependent on the\nZn<sup>2+</sup> precursor type. We systematically studied the mechanisms\nof thin film deposition on GaAs(100), including solution–substrate\ninteractions, Zn<sup>2+</sup> ion adsorption on the substrate, and\nnuclei formation as well as stress accumulation during film growth.\nIt was shown that the early stages of film formation play a key role\nin the subsequent growth kinetics and resulting film quality. X-ray\nphotoelectron spectroscopy, supported by contact angle measurements,\ntransmission electron microscopy, and energy-dispersive spectroscopy\nshowed that increasing the degree of surface oxidation and passivation\nat the early stages of ZnS film formation inhibits solution desorption.\nFinally, the previously reported mechanism of crack formation is explored\nthrough an interrupted growth series of ZnS films deposited from solutions\nwith different Zn<sup>2+</sup> precursors.