Abstract Zinc phosphate thin films were grown by plasma-enhanced atomic layer deposition (ALD) using a sequence of trimethyl phosphate (TMP, Me 3 PO 4 ) plasma, O 2 plasma, and diethylzinc (DEZn, Et 2 Zn) exposures. The film growth was monitored by in-situ spectroscopic ellipsometry. At a substrate temperature of 300 °C, linear and saturated growth was observed with a remarkably high growth rate of 0.92 nm/cycle. As-deposited films were smooth, amorphous and very hygroscopic, suggesting a phosphorus-rich composition resembling zinc phosphate glass. Upon annealing in air, crystalline zinc phosphate and pyrophosphate phases were formed.