Control growth of catalyst-free ZnO tetrapods on glass substrate by thermal evaporation method

• Various morphologies of ZnO-Ts were synthesized on glass substrate.
• Glass substrate without any catalyst or seed layer was employed.
• The effect of substrate inclination angles on ZnO-Ts structures was investigated.
• The crystal quality of ZnO-Ts strongly depends on the substrate tilt angle.
• Larger-angle deposition can enhance the nucleation and crystallinity of ZnO-Ts.

Novel three-step directions of glass substrate for catalyst-free growth of ZnO tetrapods (ZnO-Ts) without using catalyst or seed layer via thermal evaporation method were investigated. In this study, controlled synthesis of ZnO-Ts was achieved through glancing angle deposition by three-step directions of glass substrate with inclination angles of 0°, 45°, and 90° toward the gas flow at a growth temperature of 650 °C. The effects of substrate inclination angles on the morphological, structural, and optical properties were systematically investigated using field emission scanning electron microscopy, X-ray diffraction, UV–vis spectroscopy, and photoluminescence spectrum. Results showed that the substrate tilt angle is one of the most critical control parameters in determining the nucleation and growth of ZnO-Ts. This new approach provides a cost-effective and simple method for the synthesis of tetrapods, which can be useful in various optoelectronic applications and solid-state devices.