Homoepitaxy of ZnO and MgZnO Films at 90 °C

•A simple method to synthesize uniform single crystalline homoepitaxial ZnO and MgZnO films.•ZnO growth on (0 0 0 1) and (0 0 0 1¯) face resulted in films that are strongly different in their structural and optical quality.•Single crystalline MgZnO film was fabricated under mild conditions (90 °C and ambient pressure).•Mg incorporation of nearly 1 mol% was obtained while maintaining single phase wurtzite structure.

The aqueous synthesis of uniform single crystalline homoepitaxial zinc oxide, ZnO, and magnesium zinc oxide, MgxZn1−xO, films under very low temperature conditions at T=90 °C and ambient pressure has been explored. A maximum Mg content of 1 mol% was recorded by energy dispersive spectroscopy. The growth on the polar (0 0 0 1) and (0 0 0 1¯) faces resulted in films that are strongly different in their structural and optical quality as evidenced by high-resolution X-ray diffraction, secondary electron microscopy, and photoluminescence. This is a result of the chemistry and temperature of the solution dictating the stability range of growth-governing metastable species. The use of trisodium citrate, Na3C6H5O7, yielded coalesced, mirror-like homoepitaxial films whereas adding magnesium nitrate hexahydrate, Mg(NO3)2·6H2O, favors the growth of films with pronounced faceting.

Graphical abstractHomoepitaxial ZnO films grown from aqueous solution below boiling point of water on a ZnO substrate with off-orientation reveal parallel grooves that are characterized by {1 0 1¯ 1} facets. Adding trisodium citrate yields closed, single-crystalline ZnO films, which can further be functionalized. Alloying with MgO yields MgZnO films with low Mg content only.Figure optionsDownload full-size imageDownload as PowerPoint slide