The influence of oxygen partial pressure on the shape transition of ZnO microstructure by thermal evaporation

One-dimensional (1-D) and two-dimensional (2-D) wurtzite zinc oxide (ZnO) microstructures were grown on indium tin oxide (ITO)/borosilicate glass substrates via oxygen-assisted thermal chemical vapor deposition (CVD) using zinc (Zn) powder as a precursor with different flow rates of ultra-high purity nitrogen carrier gas (N2) at the total pressure of 450 Pa and temperature of 550 °C. The structural and optical properties of the synthesized ZnO microstructures were investigated using field-emission scanning electron microscopy, X-ray diffraction (XRD) and photoluminescence (PL) as a term of oxygen (O2) partial pressure. The obtained microstructure evolved from micropin to micropillar and to microsheet in correspondence with the increase of O2 partial pressure. XRD confirmed the transition from 1-D to 2-D microstructure with defects observed from PL spectra. The experiment suggested that the increase of supersaturation in the vapor-solid (VS) growth mechanism caused the shape transition.