Structural, optical, and hydrogenation properties of ZnO nanowall networks grown on a Si (1 1 1) substrate by plasma-assisted molecular beam epitaxy

ZnO nanowall networks were grown on a Si (1 1 1) substrate by plasma-assisted molecular beam epitaxy (P-MBE) without using catalysts. Scanning electronic microscopy (FE-SEM) confirmed the formation of nanowalls with a thickness of about 10–20 nm. X-ray diffraction (XRD) showed that the ZnO nanowall networks were crystallized in a wurtzite structure with their height parallel to the 〈0 0 0 1〉 direction. Photoluminescence (PL) of the ZnO nanowall networks exhibited free excitons (FEs), donor-bound exciton (D0X), donor–acceptor pair (DAP), and free exciton to acceptor (FA) emissions. The growth mechanism of the ZnO nanowall networks was discussed, and their hydrogenation was also studied.