Inference on the Production Mechanism of ZnO Thin Films from Activated Water and Dimethylzinc Molecules

Abstract

The reaction of Zn(CH 3) 2 and activated H 2 O produced in a reaction of H 2 and O 2 on a Pt catalyst and effused from a nozzle was examined both experimentally and theoretically. This reaction has been shown to be effective in the preparation of high-quality ZnO films. Laser-induced fluorescence measurements showed that radical species, such as H atoms and OH radicals, do not play major roles. The rotational temperature of H 2 O, measured with a coherent anti-Stokes Raman scattering technique, was 250 K. This low rotational temperature suggests that H 2 O molecules must be accelerated along the beam axis and that the collisional energy between Zn(CH 3) 2 and H 2 O is as high as 43 kJ mol-1. This energy is higher than the potential barrier to produce HOZnCH 3 +CH 4 , 38 kJ mol-1 , obtained by ab initio calculations at the MP2/LANL2DZ level of theory. HOZnCH 3 thus produced can be the strongest candidate ZnO film precursor.