The growth mechanisms of zinc oxide and zinc sulfide films by mist chemical vapor deposition (mist-CVD) were experimentally investigated from the viewpoint of mist behaviors and chemical reactions. The proper growth model, either vaporization or the Leidenfrost model, was studied by supplying two kinds of mists with different kinds of sources, such as H2 16O and H2 18O for ZnO growth and ZnCl2 and thiourea for ZnS growth. Moreover, the origin of the oxygen atoms of ZnO was investigated using a quantitative analysis. The role of chloro complex of zinc in the growth of ZnS from aqueous solutions was also examined by systematic studies.

Zinc sulfide (ZnS) films were successfully grown by using mist chemical vapor deposition (mist‐CVD) with fine‐channel susceptor made of quartz. For the investigation of growth dynamics, two types of mist generators and two types of susceptors were prepared and distribu¬tion profiles of film thickness were examined.Thermal efficiency of susceptor depends on heat¬penetration efficiency and line‐velocity of the mists, which are influenced by the fine‐channel gap‐height of the susceptors. Using larger size of mists requires higher thermal efficiency in susceptor to obtain a flat thickness distribution. This result indicates that the optimization of the mist size and the susceptor structure is important for the film uniformity of grown films by the mist‐CVD. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Growth of zinc oxide (ZnO) on pyrolytic graphite sheet (PGS) by electrochemical deposition (ECD) and mist chemical vapor deposition (CVD) was investigated in the viewpoint of crystal orientations. We examined the fullwidth at half‐maximum (FWHM) of X‐ray rocking curve profiles of graphite 0002 and ZnO 0002 diffractions for the investigations. In the case of ECD, thermal annealing at 400, 800, and 1000 °C for PGS before the growth reduced the FWHM value of the grown ZnO. On the other hand, in the case of mist CVD, the growth process and an etching process which may flatten the surface roughness simultaneously occurred. As a result, the FWHM values of the grown ZnO and the PGS were almost the same. These results indicate that each ZnO grain was grown on each graphite grain along with a same c‐orientation direction. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The mist chemical vapor deposition (mist CVD) method, which uses ultrasonically atomized solutions as sources, is an environmental friendly and cost-effective technology for the growth of compound semiconductors. This growth process is realized under atmospheric pressure and allows us to use many kinds of salts, complexes, and compounds with low toxicity for sources. Using the oxidizability of water including the source, most of the previous reports of the mist-CVD method are on oxide materials. In this study, we fabricated zinc sulfide (ZnS) films by mist-CVD method using thiourea-based water solutions as sources. Investigating the growth of ZnS by mist-CVD under various growth conditions and experimental setups, we proposed zinc-chloride complexes are necessary for the growth of ZnS and vaporized mist sources act as precursors.

No abstract