Improvement of m‐plane ZnO films formed on buffer layers on sapphire substrates by mist chemical vapor deposition

Abstract

The crystal quality of ZnO films grown by mist chemical vapor deposition (mist‐CVD) was improved by introducing ZnO buffer layers on sapphire substrates. The ZnO films were grown by high‐speed rotation‐type mist‐CVD with a ZnCl2 aqueous solution, which provided uniform epitaxial layers over 2‐inch wafers. To grow the ZnO buffer layers, it is necessary to form small grains of polycrystal. Therefore, we attempted to grow the ZnO buffer layers using a Zn(CH3COO)2 aqueous solution, which provides a small grain size of about 100 nm. By using the buffer layers, the full width at half‐maximum of an X‐ray ω‐rocking curve for the ZnO film was reduced from 0.69° to 0.38°, showing improvement of the crystal quality.