Catalyst/dopant-free growth of ZnO nanobelts with different optical properties from nanowires grown via a catalyst-assisted method

The paper reported a simple but effective gold catalyst-tailored chemical vapour deposition (CVD) method to grow ZnO nanowires and nanobelts with different photoluminescence (PL) behaviours. ZnO nanowires along the c-axis were synthesized via a gold catalyst-assisted CVD method through the conventional vapour–liquid–solid (VLS) mechanism. But, ZnO nanobelts grew along the a-axis enclosed with {010} and {0001} base planes without using any catalyst or dopant through the vapour–solid (VS) mechanism. The nanowires and nanobelts were proved to be of different optical quality, which was related with their growth process. Besides the different origin of the near-band-gap emission at room temperature, laser emission was only observed from ZnO nanobelts while the nanowires show anomalous photoluminescence behaviour under higher excitation density.